Servo Control in Mission Planner via SBUS out on Pixhawk PX4


in our UAV system we are using the PowerBox Champion SRS. The RX1 Input on the Powerbox we are using for the RC control to fly manually and on the RX2 we have conntected the PixHawk via SBUS Out.

We can switch between Manual Flight Mode and Autopilot but we have a problem to control the servos. At the moment we have Mission Planner as groundstation.

Has anyone already had experience with this and could support me?