Hello ...
I encountered a different problem of changing in Yaw with change in roll, when the roll changes there is a considerable change in yaw for example if the roll changes from 0 to 90 degree then yaw will be changing somethig like from 0 to -90.
I tested this with a rotatory test bench where i attached the 3d marker set on it and rotated it for roll . and finally i got the same output as above ... so please help me in solving this issue..