Central locking won't unlock

[sam271]

I'm having issues with my central locking on my 2001 ph1. The problem is that it will lock with the button on the key and by the button by the ashtray but it won't unlock with either. When I try with the key the indicators flash as usual but it doesn't unlock, so I have to use the key on the drivers door and open the passenger door from the inside handle. I have checked the fuse an that's ok.

Any help would be much appreciated.

Thanks in advance
San