Also note I think your mecanums are on backwards. They are supposed to form an "X" from the top, not a diamond (imagine extending the pins of the rollers out. They should point towards the center of the robot.
Correct:
http://www.chiefdelphi.com/forums/sh...5&postcount=10
Incorrect:
http://www.chiefdelphi.com/media/photos/20664