How to check a command response ? how to use CommandAck?


In short, I’d like an example of how using VehiculeCommandAck.
For the context, I’m using PX4 with ros2 + gazebo, and wrote a node that publish a VehicleCommand.VEHICLE_CMD_DO_REPOSITION message.
I have no error, but my drone does not move to the wanted position, and i’d like to investigate.