Could you please share with us in which scenarios the ParentOfType is not able to find the RadPane. If it is floating the RadPane no longer exists, it is a ToolWindow. This is the only scenario I can think of, that might be causing the issue. Also, the Docking control has a collection of panes - the Panes
property, which you might use.
Please give us some more details about the problem, and if possible a sample project. That will help us in resolving the issue in a timely manner.
the Telerik team