Unable to control servo using MAVSDK

Action::set_actuator()

Above mavsdk’s MAV_CMD_DO_SET_ACTUATOR wrapper is not working.

I have connected my servo in aux 1 of cube orange plus AP. i have tried values from 1 to 12 for index, but not working. Am i missing or doing anything wrong about it?

Thanks in advance.
(i am using px4 v1.15.4)