2003,all doors lock only by inserting key in passenger side door and locking

Hi, I drive a ford fiesta 2003. I am having a problem with the central locking. when using the buttons on the key, when I use the unlock button, all doors unlock. when I press the lock button, only the drivers side locks. when I stick the key in the drivers side door and unlock the doors, all doors unlock, when I lock it only the drivers side locks. the only way I can lock all doors is from the passenger side door by turning the key to unlock the door, then turning it to lock it. any ideas what's wrong with my locking system?
My car has a manual transmission.