I tried with an ancient iPod and then with a slightly less ancient iPhone but neither would work with the media interface. The operator's manual is pretty poor in regards to iPod connectivity, the instructions are basically, "plug it in."
Only thing I can recommend is checking that you're running the right firmware and your device is on the compatibility list.
Mercedes-Benz Bluetooth Connectivity
Only thing I can recommend is checking that you're running the right firmware and your device is on the compatibility list.
Mercedes-Benz Bluetooth Connectivity