I am trying to create a custom cui in autocad 2013. I created a profile & workspace. I went into the cui & highlighted my workspace & partiality loaded acad.cuix & acetmain.cuix. I go to the customize tab & click on the customize workspace in the right pane. I go to the partially loaded view to add & subtract the ribbon tabs & panels that I want but there are no check boxes. What did I forget to do?