Rc calibration failed

pre arm check RC calibration failed.?

What type of TX?
Sometimes a spectrum will have exact 1100,1500,1900 outputs and you need to set trims to 99%

I am using raspberry pi and pixhwak 2.4.8 and need to fly using dronekit without remote control

what are your params like? Also, what is the error message you get in the messages tab in mission planner?