Goliathjustin

I had an older Pioneer deck I wanted to replace the factory deck with. I went to walmart and got the removal tools. I pulled out both the cassette player and cd player, but I need to know what harness to use. I had tried two harnesses, one from Best buy, the other from walmart. Both of the harnesses allowed the radio to turn on, but no sound would work. I gave up and replaced the factory back in for the time being. But....now I can't hear anything out of the factory deck. Anyone have any ideas? I'm looking for the right harness, and if I screwed something up.

Under the cd player, there looks to be a factory amp...i'm not sure what system is in it though.
Any incite?