Panasonic CX-DP801 changer to Volkswagen GammaV (Blaupunkt)

[Burny]

Hello,
excuse me for my bad spelling - I am from Austria (no kangaroos!)

I have a Panasonic 8-disc changer which should fit to my Volkswagen GammaV Radio (Blaupunkt). Now I need a wiring diagram for the interface. I already tried simply to connect the pins of the connector at the changer to the pins of the radio. When I push the CD-button at the radio, the changer starts to work and I can hear music, but i am unable to change CD or track. The display constantly shows "CD1 TRACK1".
Are there some electronic parts needed for the interface?

Thanks for your help!

Burny