When you get this error, examine each object in turn. In that line, there are only a few of them:

1) HandRight, but this can't cause the error.
2) skeleton
3) skeleton.Joints(JointID.HandRight)

To examine them, highlight each in turn and press Shift+F9. One of them is Nothing, and that one is your problem. That's always the first step for the original error message. Once you determine which one is Nothing (it sounds like it is the third one, in this case), then the next step is to figure out why that is Nothing.

In that case, it appears like skeleton.Joints is a method that takes an identifier and returns an object (probably an object of type joint, but I don't know kinect). The object is nothing, which suggests that there isn't a joint with the identifier JointID.RightHand. So why not? I'm not sure that any of us can say.

Is it possible that the particular item shouldn't exist in the setting you are working with?