Your BMW remote is not letting you in?...

Key stopped locking and unlocking my doors (BMW diamond shape key)

1. Get in and close all doors (do NOT lock the doors).
2. Turn on the ingition and turn off quickly. (No more than 5 seconds) to start the process. Next action must take place within 30 seconds.
3. Remove the 1st key.
4. Hold the key up near your left shoulder (this is so it is closer to the remote reciever antenna - antenna is in the rear window).
5.  Hold down the unlock button and press the lock button 3 times (center button). Release the unlock button and the car doors locks automatically  which confirms the operation.
6.  Quickly repeat steps 4 & 5 for key #2 etc.

Info from BMW TIS  :)