How to move the tailestock with M20/M21

Hallo,
I have an tailstock I can move manual with 2 buttons. But when I try to write some g-code I always get an error.
My Emco Concept Turn 155 is an TCM machine and use 12 tools revolver and 6 was driven tool.
I use C-axel but I can´t find right code to move the tailstock.

I have try to write N10 G0 M21 Z75 etc.

The instructions book.
Unfortunately, it says nothing about how to deal with tailstock.

Do you now any thing about this, please tell me.

What is the error? M21, chuck must be clamped, and the tailstock prox must be set according to manual. If prox is not set it, will give error about sleeve position, check your pm.