title: Error: "Failed to map the path '/'" when I add a Telerik ReportViewer to web page
body: <p>I've just built a crap load of Telerik reports for my web site project, and they all work nicely.  I have to demonstrate them tomorrow, and tried to build a viewing page that hosts their web ReportViewer.  I have asked this question on their forums as well, but expect less response than from SO late on a Friday night.</p>
  
  <p>Whether I use GAC or bin references, as soon as I add the ReportViewer control to my page, even without trying to load a report, I get the error <code>Failed to map the path '/'</code>.  Other Telerik controls, from the Web.UI library work fine.  I'm not expecting a Telerik specific answer here, although that would ease the pain of my all-nighter, but I can see nothing meaningful in the stack trace for this error.</p>
  
  <p>How can I go about diagnosing what Telerik is looking for and can't find, or something of that ilk?  This is a serious emergency, and I will sort a 'dereferenced' bounty for anyone that can offer any suggestions tonight.  I'm going to reinstall Reporting so long.</p>
  
  <p>UPDATE:  Foolishly wary of excess complicating factors, I always try new things like this in a small, dedicated project separate from my main one.  Yesterday I quickly tried a small web <em>site</em> project when I encountered my problem.  I then tried a small web <em>application</em> project, with local, not GAC references to telerik, all telerik refs set to copy to local, and it all worked.  Naturally I was quite ecstatic, as my main project is a web <em>app</em>, not <em>site</em>.</p>