Why won't the driver's side door lock when the lock button is pressed on a remote for a 2002 Volkswagen Passat?

A driver's side door will not lock on a 2002 Volkswagen Passat with the remote if the vehicle senses that the key is in the ignition. Many cars built between 2000 and 2003 featured this mechanism so that a person could not lock their keys in the car. Try turning the key to auxiliary and then turning the key to off before exiting the vehicle.