central locking

[pug_girl27]

iv got a 206 1.6 v reg and when i try locking the car with the butto onb the fob it goes to lock it then unlocks it straight after, it does the same if i use the key in the door and it only locks if i turn and then hold the key :s its driving me up the wall,, does any1 know what could be the prob or where do i look for possible things,, thanks