Central locking with a twist!!!

[Jwf127N]

Hi all,
I have polo 9n3 base model 1.2 petrol with key activated central locking.
When I bought car central locking ( cl ) didn’t work on key in drivers door.
Google! Suggested check A pillar wires, all seem good, and then buy new door lock actuator.
Bought, fitted but same issue. Btw red light works and cl can be operated by key in passenger door and by toggle switch on drivers door inside.
Thought buying aftermarket remote central locking kit would sort.
Managed to get power to kit, as no electric window power feed. Ground easy. Unit works and clicks, but I can’t find the blue + white on/off signal wire for door lock actuator. I can see blue /white wires, 2 of them but splicing in, neither work. In frustration, because I know door can be activated by cl from pass door lock, so electricity signal must be getting to door actuator, I tried splicing every fecking wire that goes to lock actuator.
Still no luck. I have given up at the moment, but maybe, just maybe one of you bright sparks may have some ideas I could try?
Yours living in hope
Steve