IRIS doing unstable takeoff !!

[ziggBee30]

Hello

I am using ROS kinetic and i am able to send command through mavros and upload mission on my iris drone in SITL, but as i do a command takeoff using ros service call, the drone goes unstable and crashes. I just want to know what are the commands i need to give before i upload a mission !! I was successful in doing a smooth mission a while ago but unfortunately forgot what i am missing out here.

Thanks