Controlling Servos using pixhawk 2.4.8 through RC AUX

Hi. I have made a custom drone using pixhawk 2.4.8 and installed px4 version v1.14.0 through QGroundControl. I have a hexacopter with Emax Eco 2 motors and ReadyToSky ESC. My RC transmitter is FSi6X and receiver is FS-iA10B connected to pixhawk through ppm. 6 of my bldc motors are connected to MAIN pins 1 to 6. I want to use the AUX 1 and 2 to control 2 MG995 motors. I have connected an external battery to the MG995 and made common ground with pixhawk. I can rotate the servo through the actuator testing tab in QGroundControl. I have mapped channel 8 to RC Aux 1 Passthrough but the motor is not responding to the RC inputs but works with actuator testing slider in QGroundControl. I have tried to control the servos even when the drone is armed but nothing changed.
Please help me to solve this issue.