Stuck Near Side Sliding Door

[Stormin]

Hi all, I have recently purchased a 2010 Berlingo L2 van.
I am having an issue with the near side sliding door. It will not open more than 1/2 and inch. There appears to be a locking bolt or possibly a latch, below the locating pin below the main latch. I can just see through the gap that it has not retracted so preventing the door from opening. This bolt is not present on the off side door.
I have been unable to find any information regarding this bolt, and what actually activates it.
The door has been opening ok and as a result I have never looked to see what the bolt does, and what activates it. It doesn't make a great deal of sense that the near side door has this bolt, but the off side doesn't.
The central locking all works ok, and the door does actually lock. 
Has anyone ever had an issue? I have attempted to remove the liner on the inside of the door, but it does't look like it can be accessed from inside of the door.

Any information greatly appreciated.

[rnamman]

This is just a guess as I know nothing about mechanics, but maybe this locking device is only on the n/s sliding door because it's something to do with the n/s sliding door not being allowed to open when you're putting fuel in the filler pipe? I think there's a connection between the fuel filler cap being unlocked and the n/s door being kept closed.

As I say, it's just a wild guess but it might help.

[Jed Clampit]

Yes rnamman you'r right hello Stormin welcome to the forum you will have to check the fuel filler cap and opening cover it's there to stop you opening the door when filling with fuel some thing as broken cap end so it's telling the van the fuel cap is open

[Stormin]

Great. Thanks guys, I'll have a look tomorrow to see if there is a switch inside the filler. Otherwise it looks like a major operation.
I'll let you know how I get on.