OK the CD Changer has its own radio code. This needs to be put in before it will work. Have a read below, I copied it from the Audio Manual I got with my car (Ihave the 4 cd changer with the CCR600)
Decoding
NOTE: Decoding of the set is only possible with the ignition ON
1) Switch on Ignition
2) Switch off the set (radio/cass unit)
3) Press AS control and with it pressed turn on the set
4) Keep AS control pressed until you hear a confirmation beep
5) The display shows CODE and then 10 ---- after 3 seconds. The number of attempts remaining is shown (10)
6) Enter the code number (from the Car Pass or Radio Pass) with preset controls 1,2,3 and 4.
7) If you enter a wrong code number overwrite the whole number.
Example: The CODE number is 0 3 6 5
Preset controls____Display
1x control 1_______ 0 - - -
4x control 2__________ 0 3 - -
7x control 3__________ 0 3 6 -
6x control 4__________ 0 3 6 5
8) Confirm code number with AS control: Hold control pressed for approx. 3 seconds, until you hear a beep.
9) HEY PRESTO!
Note: If a wrong code is entered and confirmed:
Display shows SAFE and the remaining attempts (eg. 9 - - - - )
START AGAIN!
Now you just need the code which is usually with the radio code on the credit card sized bit of paper. On there it says CD Changer Code. Some people keep this in the owners wallet lol.
Hope this helps!