No sound coming from car speakers!?

I bought a 2003 Ford Focus with a Blaupunkt stereo. The stereo powers on normally, but there is no sound coming out of the speakers. I pulled the radio from the dashboard and found that everything is connected in the back of the stereo. I have read about radio codes, but I can't find out if that is what I need to do or is there something else preventing the sound from coming out of the speakers.

Greg
January 2010