Where do I set the motion step size, and wher do I read the joint size?

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Following he Dynamixel Wrokbench e-manual. http://emanual.robotis.com/docs/en/so...

step 5.1.ROS Section: -Operators.

Controller connects fine. when running "roslaunch dynamixel_workbench_operators joint_operator.launch" I get the following error message: "Please check motion step size. It must be equal to joint size" I can not find any documentation of where to check the motion step size, or the joint size. I am using an AX-12 motor.

This is my motion.yaml:

joint:

names: [main]

motion:

names: [zero]

zero:

step: [0.0, 0.0]

time_from_start: 3.0