central locking 1999 clio?

1999 clio central locking does not work with the key/fob.
the red light flashes when i press the fob but does not activate the central locking,
the central locking does not work when i use the key in any door but the door i use it in locks/unlocks,
but the central locking works with the button inside the car.
please help

gary
April 2010