Behringer Mixer problems

Okay. So I have a Behringer 1204 mixer. It used to work perfectly fine, but then it just stopped working. The problem is either my CD/tape output or the UCA 2000 USB Interface that comes with the mixer. I don't know which one, though. My mixer can hear the input of my mic fine, but when I put it through to my computer, it can't hear anything. It can still recognize the inputs, it just doesn't pick up any sound. I've changed all the cables and checked all the buttons and sliders. I don't really know why it stopped working. I didn't damage it in any way. I want to know what the problem is so that I don't buy something I don't need. Any help would be appreciated, guys. Thanks.

And yes, I realize this isn't really a Logic question, but you rarely get anything from the other useless forums on the web. People actually care on Apple's forums.