Set_position_target_local_ned cannot fly backward

Ground Control Software MAVLink
4

I just tested this in SITL and it is working.
Start an SITL instance and connect to it using MAVProxy, and then:
module load message
And after then:
message set_position_target_local_ned 0 0 0 8 0 -100 0 0 0 0 0 0 0 0 0 0
It just goes 100 meters backward.
Also note that, you set the velocity with that command.