Why does SiteMap.CurrentNode return null after upgrade to 4.0
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I recently upgraded a website to ASP.NET 4.0 and after moving the code to a staging server, every time i browse to a page directory like mysite.com/bacon/ the SiteMap.CurrentNode is null.  However, if i browse mysite.com/bacon/default.aspx it works fine.  The server and site are configured for 4.0 and the document defaults are set default.aspx is the first page to default to.  

I should also mention this behavior is not happening on my local dev machine, it recognizes that mysite.com/bacon/ is really mysite.com/bacon/default.aspx and the SiteMap.CurrentNode is set accordingly.  