i did imu calibrations and gimbal calibrations it could not help

it is not centering

Hi. Have a look at this thread, and wait for Natalia's answer for whether the craft should be turned on or off (my bet is off, by the way, as if the craft is on, the gimbal will fight against you when you're trying to do it).

http://forum.dji.com/thread-87837-1-1.html

Punchbuggy Posted at 2017-3-8 14:31
Hi. Have a look at this thread, and wait for Natalia's answer for whether the craft should be turned on or off (my bet is off, by the way, as if the craft is on, the gimbal will fight against you when you're trying to do it).

http://forum.dji.com/thread-87837-1-1.html

Correct, the drone should be off when rotating it.
After doing that, please calibrate gimbal with the drone sitting on it's back, so the camera is pointing to the sky directly (assume the direction that the normal-functioning-camera is pointing to as front).