Connect servo to pixhawk

I used quadcopter (generic quadrotor) f450 with pixhawk 4 , and i used pwm auxiliary pins from (aux1 to aux 4 ) , and i changed qground parameter to use actuators instead of motors, then i want to use servo , so i connected it to pin (pwm out aux 5 ) with external 5v battery, everything works good and i can control the servo from qground, but when i tried to control servo from Rc ( channel 5 ) I can’t as there is no response…. Anyone can help please ?

How did you control the servo from QGC . Did you change any parameter to achieve this .
Are you using PX4 v1.13.3 ?

I meant that once i assigned the servo to pwm aux5 , the servo test scroll appears , and i tested it that it works perfectly

Did you assign the RC channel as well?
You should set RC_MAP_AUXn, for AUX5 the default is 0 (unmapped).
Have a look here.

Yes i did assigned servo aux 5 to rc channel5 by modifying rc_map_aux5 to channel 5 , but it also does not work