there's a lot of things that might be wrong, first, did you mount your gyro at the correvct position? is your tail blades spinning the right direction?
did you try reversing your gyro switch?
Does your gyro HH works? (solid light)
if you mounted the gyro with the correct position, then you shouldnt have any problem, try reversing the switch of your gyro. if this doesnt work, try to mount your gyro the opposite side. just keep playing with it.