Technical doblo 1.9 diesel

[doughnut1973]

hi 1st time on here hoping somebody can help.:bang:
I have bought a van that previous owner had lost key,he changed the ecu and started the van by turning the switch(black cap) by hand and holding new key near the ringed plastic that fits on top of key lock.
Easy fix I thought and I bought a 2nd hand lock and key from a jtd model.I know I need to switch the transponders over regarding the immobiliser, the problem I have is when I connect the switch (plug) into the lock it fits perfect but does not seem long enough as there is a gap inside so the switch and lock do not connect when turning the key.
I just wanted to know if the plug (switch)on jtd & 1.9 non turbo diesels are different in length ? Or if there is something missing from the lock that I bought?
There is a good 5/10 mm gap inside when connected.
Thanks in advance if any one can help.