I have connected the servo to the main out of the flight control board but the servo still does not respond. Is there anything else I need to set?
How are you powering the servo? What kind of flight controller is it? It may not be providing power to the servo. Are you seeing movement on the servo page in Mission Planner?
flight controller is cubepilot orange+
Power the servo rail separately with a 5V BEC.
https://ardupilot.org/plane/docs/common-servo.html
The Pixhawk autopilot cannot provide power to the servos so an external BEC or ESC that can provide 5V should be used.
The same applies to the cube.