I wasn't getting a synch message either but kept messing with the phone, deleted it from my car and re-added, finally I was testing the voice commands on my phone and they were working, then after doing that the synch command came and now my car is synched with my phone (or at least partially synched we'll see...)
Same problem. Also Mercedes. Dealer says he has seen it before. No solution!Some BT systems sync the address book on pairing. Some need you to transfer contacts after pairing. It really depends on the BT system. Have you searched to see if anyone else has a Mercedes and experience with its BT?