Altitude Problem

Hello everyone,I have a problem with my pixhawk.when i do a testflight yesterday with my FT-goblin,i fly my FT-goblin manually and then switch to automatic.when i set to automatic,the altitude of the plane decreasing(BTW,i set the altitude at the 40m),but the motor works properly,anyone know how to fix it ?

Check that your waypoints are relative altitude, not absolute. What is the default altitude you have set the waypoints?

Post your mission file and a log file from the flight and then we can help more. Otherwise we’re just making guesses.