HTC Desire and Parrot MK6000 car kit


I've got a problem with trying to use my Desire through a Parrot MK6000 hands-free kit in my car. It pairs fine, its synced the phone book, and the parrot will do the dialing successfully (you can hear it dialling through the car audio).

The problem is that I cannot hear the other person at all when he "picks up", and apparently he can't hear me either. This is just the same with an incoming call - the radio gets muted, I hear the phone ringing (through the car audio, I press the button to accept the call, but then neither of us can hear each other.

Is it a compatibility issue?