I have a BMW E46 Business Tape/Radio Head Unit, Part No. 65 12 6 935 629. No sound comes out of any of the speakers and yet the display indicates that everything including CD is working OK. My unit works in another car but not in mine. I have, however, tried a BMW Business RDS (which is a cassette/radio only and cannot control a CD changer) in my car and that works fine. All the speakers work OK. A BMW specialist spent all day trying to find the fault without success. I suspect it is a wiring issue but don't know where to start. Can anyone please help? Thanks.