Well, dunno then.

But.. my docks use a MALE (pins) DB-9 connector, for use with the exact same serial cable that came with the Empeg/RioCar player. Are you doing the same?

See, the odd bit is, if one gets the pinout backwards, the middle pin (3) will still be okay, but the other (2) will be wrong, possibly giving one-way communications.

Cheers