how to mix channels on a dx3r?

[patxeik]

thanks gee.
I have tried to set it +100 in one side and 0 in other and again the same, doesnt work.
The servo is working fine in another channel so maybe the auxiliary channel is broke.
I can do it with a y harnnes but i want to mix it cause i have a dx3r for something
Anny help will be much appreciated.
Thanks