Hexa doesn't execute command in guided mode

Hi everyone,
I’m currently student and want to command my drone just with my Custom Ground Station so I turn the UAV in Guided Mode and send him some command like ARM, SET_SERVO, SET_MODE, REQUEST_STREAM_DATA … and it works good.

After that I send some command like NAV_TAKEOFF, NAV_LAND, NAV_RETURN_TO_LAUNCH , it responds every time a acquittance message with a status of 0 ( in MAV_RESULT it’s mean he accepts and executes the order ) but when I plug the battery and test the function outdoor, it doesn’t move and always responds me a acquittance of 0 from my command.

I work in C++ on Linux, I use a telemetry 3DR to connect with my UAV and thee firmware is 3.4.4

Thanks in advance for your help.