RF8 and flight axis, missing throttle

Hello!

I have an question. I hope i can ask here. I can fly with my RF8 and everything is okey. But if i choose in Mission Planner SITL then my throttle is going automaticly zero. Everything else works, Yaw, pitch and so, but i see mu interlink showing, like i’m holding throttle down, but i move it around, but nothing happens? Can someone help me why?

Regards

Have you armed the throttle?