Door wiring loom problem with sound

Can anyone shed any light on a problem.
Wanting to upgrade his doors to 10 pin mirrors, a friend of mine has changed the complete door wiring loom. After doing this the sound has ceased to work. He has connected new amps and has an after market stereo but no sound.
The car had standard wiring loom in the door. The sound on the side that still has this fitted works perfectly.
Can anyone shed any light on this please?

not knowing which car is tricky but logic says there must be different pins in the two sets of connectors worth checking the pins on the two looms starting at the door hinge connections

If the Donor car was after 99 and the recipient is pre 99 you will have problems. The later models have a single amp in the boot rather than separate door amps.

Concur with Sandy and Rewmer; if it's a cross-over then probably need to re-figure multi-pins - totally different systems!

his car is 1996 - DT
Donor loom is 1996 - HSE
Mirror works perfectly as his brain was changed a while back for all singing and dancing 2002 brain.

Did the donor car have Harmon Kardon sound system? If so likely that this is the issue as not compatable with aftermarket head units.

It did have Harmon kardon, will pass on all your helpful comments