Thank you profimc. It worked for me.
But I have an additional problem. I can't use throttle. The calibration fails for Channel 4 & 5: Channel not centered.
When in simulation mode, Channel 5 will trigger flaps. Channel 4 (throttle) does nothing. The radio picture on MultiFlight always shows -100% for Channel 4.
What can I do?
Is my (new) Smart SX receiver faulty?