No signal on S-BUS OUT port on the Pixhawk 4

Question

I have a problem/ question regarding the S-BUS OUT port on the Pixhawk 4. My setup is as it follows:

transmitter: Radiomaster TX16S with RFD TX-MOD v.2 receiver: RFD 900ux 2.0 a rover with 2 stepper motors Mission Planner for mission command. The rover I have can only accept 2 protocols: IBUS and SBUS. I connected the receiver to Pixhawk 4 in the TELEM1 and DSM/ SBUS RC ports. On Radiomaster I selected the External RF as S-BUS. The binding is made and in Mission Planner I can see the inputs in Radio Calibration.

The problem is as it follows: To send the signal from the autopilot to the CPU of the rover, I use the SBUS OUT port of the Pixhawk 4. The problem is that the CPU doesn’t receive the signal and the rover doesn’t move. I also want to mention that if I connect the rover directly to the receiver, it register the signal and the rover move as intended. How can I make the rover move using the SBUS OUT port?