Spinning the Robot with Mecanum Wheels

[Teammax]

We are having major problems getting the robot to spin with mecanum wheels. I beleive the code is correct as we consulted a power point from here that verifies our program matches the work of others.

The robot goes forward, backward. side to side, and at an angle just fine. But, when we try to spin it the robot just vibrates a lot. We did try putting wieght on the wheels. Has anyone else had this problem? Any fixes the might work?

Thanks in advance

PS if there is an old thread that addresses this issue I didnt find it and would be happy to go there if this was covered