Autopilot: pixhawk 4 mini

Dear people
I do have a question about the pixhawk mini and Qgroundcontrol.

After updating firmware via QGroundControl to
px4fmu-v1_default.px4 i got the problem, that my RC-Channels were not recived.

I tried to do the radio setup with my pixhawk. However, the message in the topic shown.
Detected 0 radio channels. To operate PX4, you need at least 5 channels

I am using a FrSky R9 long range receiver, The R9 is binding (Green LED is on), but
QGroundControl complains about 0 channels detected

Thank you for your time and attention

Best regards,
Minh T Tran