Warning : this is a case of the blind leading the blind
UPDATE : Declans blog explains that you need to use F2 to change the element name
Quite possibly ignore the rest of this !
When you rename a custom control such as the prtView in xpages you will get error messages such as “NotesException: A required argument has not been provided ” in the browser if you have debug enabled ( if not go find out what it is ) or “The unknown tag xc:xxc cannot be used as a control”
The problem is that when DDE renames the main design element it does not rename all of the attributes in the background.
You can fix this by using the eclipse navigator to make the changes in the back end manually