iPhone contacts on iDrive incomplete

[GERMANIKS]

My iPhone 4S contacts don't completely sync with the idrive of my F10 520d. I've got 274 contacts on the phone and about 10 - 15 of them won't appear in the phone book of idrive.

Any ideas why?

Make sure those names do not have special characters, like ', " )
Also make sure the phone number do not have brackets like: 00353(0)8797

That is what I would check first