I just figured out what is causing it. In my web.config I have the maintainScrollPositionOnPostBack setting turned on for all pages. That was causing your control to error out when trying to load. I didnt see it until now because my error handling was recording errors that I did not notice until now. The error that was occuring was:

 

The MaintainScrollPositionOnPostback page directive cannot be set without an htmlform.

 

Once I turned it off, it worked just fine. I can probably turn this off for just your control, right?