Audio Additives Stylus Force Gauge inconstantcy

I recently purchased an Audio Additives Stylus Force Gauge and it is driving me nuts. I get inconstant readings every time I lower the stylus onto the little black dot on the plate. Without moving the arm, every time I lower, raise, lower, etc., I get a different reading between 1.68 - 1.88. The batteries are new, device reads 0.000g at start up, calibration checks out using supplied weight, room temperature is 72F, no interference from tonearm lifter and everything is level.
Anyone else have this problem?
Put a pair of Depends on it. Should do the trick. Or let it out with the dogs. 
Go onto Amazon and take a look at the Riverstone Audio gauge. $28.95, none better.
Agree 100% with @bdp24 

Bought the Riverstone few years back and never looked back.

Extremely accurate and repeatable, really like the drop down bracket so stylus is then at same height it would be playing vinyl.
My experience with these repackaged generic gauges like the one you are using is that they are all unreliable - perhaps its some form of magnetic interference (i.e. this is why it measures fine on calibration weights but goes haywire with a cart)

The Riverstone that others cite likely does not suffer from this due to the added mechanism offsetting the location point and getting the cartridge magnet away from the weight mechanism. 

These days I use the Rega Gauge which eschews magnetic materials entirely and works a dream but it is rather premium priced  
I watched someone doing a setup where three different digital scales were used and none of the scales agreed (the user averages the readings).  None of the scales were low-cost models, one was a Win scale that is made for cartridge setup and costed about $900 more than 15 years ago.

I don't know what to make of this.  I use an outrigger that rests on the scale which has an attachment that can be set at different heights so that the measurement is taken at the level of the record.  This also means that the cartridge is never close to the scale itself (the outrigger is acrylic).  I don't know if this improves accuracy, but, it certainly removes issues involving magnetic attraction of the cartridge to components in the scale, and incorrect readings from the cartridge being at the wrong position (height) when the measurement is taken.
Exactly Larryi.

I never even thought about the magnetic part of measuring on the outrigger bracket, just the fact that it now sits at correct height but it certainly could be a part of it.
To the OP:  Lower the cartridge (preferably an MC cartridge, because they have big magnets) until it is barely above the weigh pan but not touching it. Does the gauge show a negative weight value?  If so, that indicates it contains some low level of iron; the magnet in the cartridge is pulling UP on the pan.  If the weigh pan is magnetic, even a little bit, that messes things up.  I used one of the popular digital scales for years before realizing that it had the problem, which was only evident when I tried to adjust VTF for an Ortofon MC2000 cartridge, which has a humongous magnet situated in its belly, near to the platter or any weigh pan.  I subsequently bought one of the 2 or 3 gauges made by Ortofon, the weigh pan of which so far seems to be non-ferrous, although it is metal.  This problem seems so easy to avoid in designing such a gauge.  But apparently the sellers do not care a fig.  As long as they're selling.
I still use the old Technics that came with the EPA-100 arm. It's electronic but analog, not digital, and doesn't give you milligrams (which are SO important). It's just a needle that swings from .5g to 3g, with markings for each .1g — and I can squeeze the needle between them for .05g. Accurate enough for me, and utterly consistent. Not high tech, but cool in a retro way. 
That is a very big discrepancy; it’s normal to have some minor discrepancy with any of these gauges and especially those that have 3 decimal point resolution but that is huge. Also, try to hit the centre of the dot each time.

In light of the fact that scale takes triple A batteries, I would replace the batteries first to see if that might fix the problem if you are using those that came with the scale. You may already have some extras around; if that doesn’t correct things then, yes, look for a new scale.

The body of the Riverstone gauge---they actually make two, but get the one with the extension arm which puts the stylus at playing height when measuring VTF---is made of a tough plastic, and that extension arm of a non-ferromagnetic grade of stainless steel. The gauge has resolution to 0.005g (!), and can be recalibrated to zero via the 5 and 20 gram weights included. Riverstone Audio has a video on You Tube in which the gauge is displayed, described, and explained, and then demonstrated.

The ubiquitous electronic gauge that most companies are rebranding and marketing as their own is, in comparison, a piece of junk, regardless of price. Many of them sell for more than the Riverstone, some much more. I mean come on, $28.95---whaddaya got ta lose?! For more details, see the Riverstone Audio website. 

Another possibility is that it’s telling the truth, as in bearing issues with the arm.

No mention made of the type of tone arm.  If a unipivot that possibility is out.
Just switch to the good old reliable Shure SFG-2. Never goes out of calibration. 
The Transcriptor scale is perhaps the nicest vintage scale 
I have owned and built like a fine instrument.

That said I still need to have batteries in the drawer for
the more modern options.
What you purchased looks like a re-branded cheap scale that is sold all over ebay for under $10.  If it is giving you inconsistent readings, toss it and look for something better.  Lots of suggestions here.  I use a "MY Weigh" scale.  It is not a stylus scale and has to be fiddled with to do the job well but it has been excellent over many years.  You do not have to spend a great deal of money to get something that works well.
It doesnt matter how many zeros follow the decimal. Accurate and repeatable scales aren't inexpensive. Sort of like spirit levels. Buy one for a dollar or buy one calibrated for cnc machines for many hundreds. No free ride here
Personally, I have not had problems with the Canrong scales over the years. These are the scales commonly referred to as the cheap, Chinese, rebranded etc. 

The first one I bought had .000 grams resolution and I think I paid about $50 about 10 years ago. It shipped with virtually dead (button) batteries (which is why I suggested replacing original batteries above) but once those were replaced the scale functioned perfectly for about 7-8 years before biting the bullet. 

For what it's worth, my wife was a researcher at that time and I had her take that scale into work and test it against a couple of scales in that lab that cost between $1500 and $2000 at the time. The variation between the Canrong and the expensive lab scales never exceeded .007 grams doing a number of measurements between one and five grams. So good enough for me. 

When that one stopped functioning I was feeling a bit frugal so bought one of the lower resolution scales (.00 grams) off ebay for about $10. Anecdotally, I do feel that the higher resolution version was built to slightly higher standards-notably, the weigh tray on the more expensive version seemed to be straighter, less canted. 

But I have two of the cheapies here and they register within .02 grams of each other; that is certainly acceptable to me. So I don't think it's necessary to spend huge amounts of money on these, or any scale to get accurate repeatable results.

But easy to get a bum product with anything you order. Hopefully the OP got this sorted out. The post about it possibly being the tonearm (and the scale being accurate) was interesting and a possibility that I did not consider. Small differences in height in terms of where the measurement is actually taken can be a factor with unipivots and/or arms with low slung counterweights but the difference the OP experienced does seem extreme. 

I'd be curious for him to weigh back in (no pun intended!) to hear if he's resolved the problem. 

All that being said, the Riverstone at $29 does appear to be a very good value and option. Looks good. 
There are many gauges out there however the Winds ALM01 is by far the best to 1/100th of a gram.However i don’t know if its still available.It is costly at $800.00 however it is by far the best.
@melm- If you owned an AV Designhaus Derenville VPM 2010-1(about $650K) with(say) an Air-Tight Opus 1 or Koetsu Coralstone Platinum($14-15K ea) mounted, you wouldn’t be asking that. Some of, "we"(though: not me) have that kind of scratch, for lab-quality instrumentation(God bless 'em).
As I stated above, the Canrong I used for 7 years that cost $50 10 years ago was "lab quality instrumentation".

Clearly. And considerably more resolving and accurate than the Winds. One might argue, I suppose, that I just got lucky and got a good sample. But it was. 
I’ve never liked those type of scales either. The Mapleshade scale is very accurate but not great looking. Pierre has modified a jewelers scale to accept a (loooong) platform which is one of it’s drawbacks. I too use the Rega now. The Shure beam scale is very inaccurate, I couldn't believe it when I read not too long ago, MF was endorsing it.
Ditto what ebm said. Upon recomendation, I found a used Winds ALM 01 for $300. They are no longer made but you can find them. All the incosistancies went away. It is the best and I've tried many.
"The Mapleshade scale is very accurate but not great looking. Pierre has modified a jewelers scale to accept a (loooong) platform which is one of it’s drawbacks."

Mine is 10 years old, and working fine. As long as fresh batteries are in it, I seem to get consistent measurements anytime.

The platform is kind of hokey, and I've had to reglue it several times from knocking it loose. Otherwise, it does what it's supposed to do.

Thank you to all that have chimed in to my post and much appreciated is the Riverstone Audio gauge recommendation from bdp24 and Uberwaltz. I ordered one from Amazon and used it over the weekend; sure enough the Riverstone is a good scale and offers consistent results - hallelujah! One thing I did notice, however, is that it takes longer than 30 seconds to warm up and settle down. Leave it on and use it for about 5 minutes before final result becomes accurate and consistent.
I am using a unipivot VPI 3D printed tonearm with dual pivot mod. The cartridge is Lyra Etna.

@seasoned, one thing to be aware of about the Riverstone gauge is that it is so sensitive merely breathing near it will change the reading. A ceiling fan, wind from an open window, even moving your hand can change the reading. So, set your stylus down, stand still and hold your breath, and take a reading!
I use the ortofon digital scale and believe it or not, the old shure scale works great
Bought the Riverstone few years back and never looked back.

Extremely accurate and repeatable, really like the drop down bracket so stylus is then at same height it would be playing vinyl.

Unfortunately the Riverstone will not work with carts like Benz that use very powerful magnets. I tried it with my Benz Wood SL and it exhibited the classic "negative read" as the cart approached the landing zone. Both on the body platform and on the accessory arm. The folks at Riverstone confirmed they had received some reports about this with carts like Benz. I was disappointed because I otherwise really admired what Riverstone did with the design.

I used the Ortofon and it was so unreliable I threw it in the trash !
The Shure is fine to 1.5 , over that a PITA .
By the way...

@melm- If you owned an AV Designhaus Derenville VPM 2010-1(about $650K) with(say) an Air-Tight Opus 1 or Koetsu Coralstone Platinum($14-15K ea) mounted, you wouldn’t be asking that. Some of, "we"(though: not me) have that kind of scratch, for lab-quality instrumentation(God bless ’em).

This Dereneville VPM 2010-1 is not for sale - it’s never for sale!It’s just a prototype for testing.No one can buy it.

Cheers Rainer
from AVDesignHaus
Aside from the magnetic interference lewm mentions the problem might not be the gauge. A tonearm with bad vertical bearings will do exactly the same thing. Get one of these,

Take repeat readings measuring the distance of the weight side to the platter. If if varies at all you have a problem with your tonearm. There is no way a scale like this can be off unless the weights are bad.
You could also buy another digital gauge and if the readings are consistent the gauge you have now is defective. But, as has been mention the cheap digital scales are a risk. Like Lewm I also use an Ortofon Gauge. I check it once in a while with a calibration weight. I always get consistent readings. The Platform is stainless steel which is not magnetic. 
I forgot to mention, if I were going to buy another gauge I would get the Rega Atlas Gauge. I like the way it locates the stylus in a little cup and it is obviously a much more serious piece than the Chinese gauges looking at the internals. 
@derainer-      I said, "IF" (iow: hypothetical).     That it exists/existed indicates SOMEONE owned one.      Apparently: at some point you assigned a price(s), or- these articles would not have made mention of it:   (         (                                                                                                     (                  Don't be mad at me, because you were never able to sell one!
I tried two different scales branded Ortofon and the cheapest is the best! ORTOFON DS-1 is what I like
Only 1 from 2 different Ortofon digital scales work flawlessly and it was cheaper model. The more expensive Ortofon scale was defective power sucker that can’t measure anything - bad quality for higher price.