stereo not working?

[infinitezero]

Hey,
       Just picked up a new stereo for my 87 rx7.  The original stereo from it would put out sound, but just didnt play MP3 Cd\'s.  So i install everything, and I get no sound from the speakers.  Any suggestions?  I believe everything is hooked up as it should, and the speakers and everything worked fine before.  As you can see I am a lil baffled.  sorry if this is in the wrong thread and whatnot.

Andrew