I bought the special cable for use between two 12FG's, and it works, partially.
On the trainer side I don't get the same trim settings and functions like butterfly/crow as the teachers model is set up with.
I have tried all the varables, func, mix,normal, on each channels. (8ch RX and PPM)

What can be wrong?

Stein
Norway

You need to make sure the student transmitter operates the model the same as the instructor's transmitter. Differences between the transmitters will mean that there will be slight differences in ATV's, trim settings, sub-trims, and so on. You have to set the transmitters up so that the controls on the model operate correctly. Making the transmitters have identical numbers in their programming is a start, and you fine-tune from there.