Central Locking Issues

I have a 52 plate TD5 Discovery, and my central locking doesn't work. The key fob will arm and disarm the alarm but will not unlock the doors. I can only open the drivers door with the key and none of the other doors or boot will unlock. So we can not use them, which is rather inconvenient. Has anyone got any ideas of what this may be??

the switch from the dash has no effect at all? push it in a silent environment and listen carefully...do you hear something? ... if nothing check fuse F1 interior fusebox, if no joy we'll speak then