Mk1 Tail lights upgrade

[Mk1- Trend]

Hi

Any advice on what could be the problem , I am currently changing mk1 original spec tail lights to the new spec tail lights . I have got the adaptor / harness to do the conversion .
When plugged in to original tail lights the system / configuration works perfect . As soon as I change to the new spec lights using the adapter the lights goes on but configuration is out …..( reverse lights stays on but vehicle not in reverse + indicator lights stays static etc)

Any advice on what the problem can be . Greatly appreciated.

Cheers

[buggyfan]

Wire pinouts on the adaptor plug is wrong.