What version of Wingstabi are you using, classic or easy?
I have a model with dual elevator servos using the classic firmware, I just allocated them to elevator control in the Wingstabi setup and both servos respond to the model movement.
If you are using the Easy software you will need to transmit both channels from the transmitter, i.e. if the elevator servos are on Rx ports 2 and 3, then you need to send elevator signals on channels 2 and 3 from the transmitter.
