Multispace rear door latch

[lakeside]

Sorry rear door.
I have 13 Reg Multispace and although it is okay at the moment, the rear door closure catch did seem to get out of sync recently. The small bar came across and therefore would not move or close; I eventually moved the bar and it worked, however it happened again and this time I think I moved the bar in a different direction and it locked so I couldn't move it or close the door. After half an hour the wife came along and closed it with more force and it worked.
I wonder what is going on here. I do hike in some wild places leaving the car so would not want to be stuck with it unlocked. As back up I wondered about an S shaped bar that would keep it closed from the inside. I recall you can buy such a thing to get ventilation during the night but I think I could fashion one. I would welcome comments.

[cancunia]

Maybe the lock is not opening enough to latch the lock open, but just enough to allow the door to be pulled open? Some WD40 or similar might help.
I can't remember how the locks work, but if the tailgate is open & you close the lock with a screwdriver, does it unlock when you try the button in the handle?

[lakeside]

It is working now so reluctant to fiddle. Previously when I tried the ignition key central locking it did alter the catch. It it happens again I will try the screwdriver and button in the handle option; thanks I think you might something.