The "Add Diagram" link on the menu bar seems to be shown based on having the create/edit page permission. But to create a Gliffy diagram users need the create attachment permission as well. If a user with create page permission but not create attachment permission clicks on the add diagram link they get a blank page. The error in the log is: 2008-02-17 21:15:01,750 WARN [http-8080-Processor4] [com.opensymphony.xwork.DefaultActionInvocation] executeResult No result defined for action com.gliffy.confluencePlugin.action.AddDiagramAction and result pagenotpermitted