1997 106 Central Locking

Just a quickie if anyone can help with the central locking point of things.

Basically - it doesn't work.

When I'm in the car and pull the driver side lock knob up, usualy the locking should lock the whole car. It doesn't.

When I press the button on the key, the locking should work - it doesn't.

However...

When it DOES work, it goes mental, and keeps unlocking, locking, unlocking, locking etc...

Any suggestions?? :banghead: