(Solved) "boot" central locking not working.

[Tom MrTom Willans]

Since I am doing a mini conversion on the van, and want to be able to get out of the back doors, I have just purchased the parts to add an internal handle to the barn door (door card, handle and mechanism).
The problem I'm having is that the replacement mechanism doesn't seem to activate the central locking.
I can lock the door fine with the key, and if I lock the front doors, the central locking will lock all the doors, including the back one.
However, if I lock the back door, the sliding doors will stay unlocked, and the lights don't flash to show it is locked.
If everything is locked, I can unlock the back door, but it wont unlock the side doors until I actually open the back door. Then it will behave the same as if I opened one of the doors from the inside.
The original part was black and white, the replacement black and grey (with the extra cable). I can get part numbers from them if needed.
On opening both parts, the internal handle version has a motor in that can control the internal handle lever (for what reason I can't work out), and an extra wire going into a block of white resin looking stuff.

Should it just be a case of swapping the parts in, and it should work, or do I need to swap some wires around?
If anyone has the pinout for the connector, it would be greatly appreciated.
Many thanks.

Just found that with the door open, the central locking locks, then immediately unlocks the side doors. Also with the latch partially closed. But with it fully closed, nothing happens.