Should work. I have a ridax ipod station connected to MCL 2AV and MCL 2P. When I plug the ipod into the station the system powers up and I control the ipod in A-TAPE mode. Works great.The system is a standalone and not yet connected to an audiomaster.
Did you try to reboot the whole system?
Is your MCL 2AV in L.Option 1 or 2?
Try to control the MCL 2AV with BC 9300 disconnected.
Otherwise it could be, the MCL 2 AV doesn`t detect your mp3 player because datalink is missing at the source.
Try to connect another source - Beocord 4500 or something like this- to the MCL 2AV (if you have).
Good luck.
Stefan