[nyaculak]

Like Joe Ross said, your code only evaluates the value of the axes once, before teleoperated mode is ever started. To fix this, you need to retrieve the values of the axes you wish to use at the beginning of the teleop loop.

Also, for a mecanum drive robot, you want to call a mecanum drive function instead of the tankDrive() function. The RobotDrive defines two mecanum drive functions: mecanumDrive_Cartesian and mecanumDrive_Polar. Take a look at the Javadoc to learn how to implement them.