When you use the key in the drivers door it physically moves the lock so unless superlocked you would expect it to work.
There are 3 switches on the lock actuator in the driver's door: one is for the central locking motor (when you use the remote); one is for triggering the other central locking motors (when you manually lift/lower the lock from inside the car) and one is for when you enter the EKA code.
If no response from the remote at all and if moving the passenger door lock manually has no effect on the driver's lock then the locking motor inside the actuator has probably burnt out. There is a tiny little ring inside the motor that the brushes touch and this seems to break up very easily.
Similarly, if passenger actuator refuses to shift short of manually lifting / lowing it then that motor is probably done for too. If so, you want to start looking at the RF receiver and check it has a green dot on it and the part number matches up with the latest model. If it doesn't then replace it!
If that doesn't match your symptoms then let us know the circumstances in which the front central locking is triggered.
Hope that helps,
J