Parsec

This is for anyone who has some experience w/Eclipse HUs. I bought a 5423 used off someone and installed it today. I have 2 external amps for spkrs and sub. The HU plays the radio just fine, but when i inserted a CD, it wouldn't play. So I press FUNC + '6' and entered the key CD he gave me and it said 'ERR' and spat it out. I'm not sure if this has anything to do w/the ESN feature cuz I think it would disable all functions including radio, not just the CD player. Does anyone have any ideas?

PS - I hooked up my PS2 to it and I can play DVDs just fine through the AUX jack on the HU also. Just CDs aren't recognized for some reason.