samples not playing

I'm having a problem here with samples from one track not playing after adding some more to a different track..

had this problem before but can't find it back in the forum.

the voice monitor looks alright. What could be the problem?
Anybody remebering the thread from a few months back?

going nuts now have gig on friday

Set the whole program to poly, not mono.

mmm problem not solved.. Think I'll make it less complicated for now: work with a complete backtrack plus some midi to my synths..

make sure the samples are 44.1 khz and 16 bit?