When I bought my new A4 it came with 3 remote keys and 2 valet keys... no plastic emergency key or key tag. 2 of the remote keys work fine, as does one of the valet keys. However, the remaing remote key and valet key won't work. They fit the locks and ignition but neither can be used to start the car and the remote doesn't lock/unlock the doors when the buttons are pressed. I've tried to reprogram the 3rd remote as per the manual but it doesn't make any difference.

Any ideas...?