I have a 9CAP with a r138dp 8 channel receiver. I am using 7 channels... 1 rudder, 1 throttle, 2 elevators, and 2 aileron. My question is with the ailerons ( channel 1 and channel 7) when I run the servo test, the range of aileron movement is the same on both channels/wings and considerably more on channel 1 than I can achieve when I try to set endpoints. Even at 140% channel one has considerably less travel than channel seven. Aileron differential is 100% on both channels. What am I doing wrong? About 30 degrees up and down is available in servo test, but maybe 10-15 degrees otherwise with channel 7 (aux) aileron having much closer to full range than channel 1.

Mike