DO_VTOL_TRANSITION api isn't work

Dear All,
We use simulater(RealFight9.5) and this plane(fightaxis) to simulate vtol plane.
When we use COMMAND_LONG API to send MAV_CMD_DO_VTOL_TRANSITION, COMMAND_ACK response MAV_RESULT_FAILED.

The following is we use the method in Guided mode.
We use arduPlane V4.3.0dev.


Do you know why and what is wrong?
Thanks