Fix Mondeo Mk2 Remote Locking Problem?

Can anyone help with the following problem?

Using the remote key (2 button type) the central locking will lock/unlock all doors except the driver's .

Using the same key in the driver's door lock, the central locking will lock/unlock all doors operate normally.
Is there a direct electrical connection between the in car remote unit and door,which if failed, would prevent the driver's door operating, or is the control purely down to the remote unit telling the central locking unit which doors to operate?

Any info would be appreciated.