Citreon Synergie

[dl56uk]

i have a 1998 citroen synergie and the drivers passenger sliding door wont open when the handle is pulled from either the outside or the inside. The catch moves up and down whenthe car is locked and unlocked by the key. But the door remains locked.As its a sliding door can the door panal be easly removed from the inside when the door is in a closed position ? If the panal can be removed any ideas why the door remains in the locked position ?