Central Locking

Hi, please can someone help? The central locking on my 320 Convertible is stuck in the locked position, except the drivers door, which will not lock! I've checked the connections inside the door and there does not appear to be any power getting to the electrical connector on the latch mechanism. The fuse is ok. When I try to lock the drivers door the lock turns fine but the button stays where it is. Any ideas as I'm desperate?

Thanks

Dave