Vtol duo tailsitter

Hello there. I have built this kind of airframe. Pixhawk px4. In MC mode when I try to take off, plane nose up, the motors give different thrust to achieve vertical stabilization. My problem is that motors in that position should be commanded by yaw oscillation, but they actually are commanded by roll oscillation.
This makes impossible the take off. I am probably missing some basic setting…
Does anyone know what is wrong?
Thank you very much

I don’t quite get your issue. For a duo tailsitter, roll stabilization is achieved by differential motor thrust, and yaw by the elevons, no?

Thank you for answer.
Yes, what you write is what expected.
But my vtol had strange behaviour on the bench.
Now i think i have fixed the problem with levelling the horizon in fixed wing mode…