From the screen shot it looks like you already created one. Did you delete it and then try to recreate it? Or delete one part of the service and try to edit.
Try creating one with a new name/prefex.
A great thing about clearpass is that it is very flexible, but if you have not taken any of the training classes and try to just build it on the fly it is very challenging. Clearpass should be setup by one of the cetified partners or an aruba employee either onsite or remote.
If the above dosent work then please contact TAC.