hooked up TT and preamp to receiver sound fades out after 4-5 seconds


I just bought a realistic lab 400 turntable and hooked it up to my receiver a pioneer vsx 56txi into the phono input. I will add that I am a total newbie to this. I got nothing no sound at all. I researched and bought a phono preamp behringer PP400. I hooked it into the phono in on the audio of the receiver and connected the ground wire and had sound for about 4-5 seconds and than no sound. I tried connecting to the cd audio in and same thing only sound for about 4-5 seconds. Everything else works fine regarding sound. Stumped. I would appreciate any suggestions you might have.
atrust
Exactly! noromance is correct, once you purchased a external phono pre amp you need to use one of the normal line level inputs like...CD or AUX or Tuner or just about any input will work as long as its not the internal phono. 
The OP states that he tried hooking it up to the CD input, but the same thing happens.

I looked at that receiver.  My lord does that have a bunch of crap on it.  Most AV receivers need to be set up right from the beginning to work with non surround/video sources.

IMHO, there is something in the receiver's vast menu, not set up correctly.
From the manual.  This might be why your TT  didn't work plugged into the phono input the first time, (before you got the outboard phono stage).

  PHONO/LINE Setup • Default setting: PHONO You can choose whether you want to use the PHONO jack on the rear of the receiver to connect a turntable, or a line level component (such as a CD or DVD player).

1 Select ‘PHONO/LINE Setup’ from the System Setup menu. The current setting is highlighted in the display.

 2 Select either PHONO or LINE.

 • PHONO – High level setting for turntables (without a built-in equalizer or pre-amplifier)
 • LINE – Line level setting for all audio components other than a turntable (except those with a built-in phono equalizer

 3 When you’re finished, select ‘Exit’. You will return to the System Setup menu.
@mofimadness That's what makes this board great. Amidst the sturm und drang and other noise, these thoughtful, methodical solutions and thoughts still surface.
Yes thank you mofimadness. I did all that you said at the beginning. I tried phono first , than changed it to line. The same result. Than I went to cd and did the same thing, same results. That is why I am pulling my hair out. That is when I posted here and walked away from it for the day before I end up with a flying TT. Thank you for your responses. I will start over and try again sometime today.