Trigger Trouble

I decided to take advantage of the option to use the trigger feature to turn on both my Parasound amp and preamp with a single switch.  I followed the directions in the owner’s manuals and used the cable provided with the equipment and . . . nothing.  I switched the cable to see if either the preamp switch or amp switch would control the other.  Didn’t work either way.

I went on-line to research solutions and found posts from a few years ago that stated that the trigger feature needs a grounded power connection to work.  As I noted on another threat, my old home only had two prong electric outlets, and I had an electrician swap out the electric panel surge protectors for ones that legally allowed me to use three prong outlets, even thought there was no ground.  Other members have urged that I have dedicated, grounded lines installed for improved sound.  Apparently, that would also allow triggering to work, if what I have read is true.

You think so? 
I found an error on the Parasound A21 manual page 8:
" 2. Plug the other end of this wire into the external DC source. "
the picture shown the control component plug into the " INPUT "

The correct connection should be connect the 3.5mm 12V trigger cable to P5 preamp 12V Out, Turn on options switch to manual.
On the A21 plug the trigger cable to 12V Input and switch position at 12V.

This setting will allow the preamp to control the power amp.

@imhififan:   Exactly right!  I did just as you instructed and it works now.  👏.  I will put a sticky note on that page of manual so that any future users will know how to do it.  Thank you Sir!

Yet again I benefit from solid advice from the good people on Audiogon!