I have a new Futaba 6EX-2.4ghz transmitter I am trying to mix dual elevators with so they move exactly the same. One servo is plugged into channel 2, the other is plugged into channel 5 (which has a switch designated for landing gear). I am able to mix the channels partially, but it doesn't seem to want to work properly. I can mix it so deflection in one direction works as it is supposed to, but deflection in the opposite direction doesn't move the mixed in channel at all. I have a feeling this has something to do with this channel being designated for landing gear normally.

I can't use channel 6 because I have both aileron servos plugged into 1 and 6 (the only way they can be set up for flaperons). Is it feasible to use a Y plug on the dual elevators instead of channel mixing? With Y cables, can I be certain the servos are moving the exact same? Where can I find a Y cable that moves servos the proper way for two elevator servos (facing oppsite directions)

Any help is greatly appreciated!