hello i have a 99 4 door focus problem started saturday central locking works but not on drivers door can lock car if inside button pushed to lock and central locking works fine, but if use button on key 3 of the doors try to lock but not drivers door so central locking wont stay locked have to open back door lean over and press lock from inside then everything ok the same opening car central locking unlocks but not drivers door any help please driving me nuts thanks in advance