SSRS2012 : User '' does not have required permissions

I finished implementing the Microsoft SSRS2012 security/authorization extension sample as documented here.

The Login seems to work but then right after login, I get authorization error on http://devsql3/Reports/Pages/Folder.aspx

"User '' does not have required permissions. Verify that sufficient permissions have been granted and Windows User Account Control (UAC) restrictions have been addressed. "

class Folder Page

.

.

private void Page_Init(object sender, EventArgs e)

{

.

.

  if (!base.RSUser.HasPermission("Read Properties")) 
  {
                if (flag)
                {
                    throw new InsufficientPermissionsToRoot(this.Page.User.Identity.Name);
                }
                throw new AccessDeniedException(this.Page.User.Identity.Name);
   }

"

I can look at Identity.Name but it is empty in code as well as the error message.  It's like there is a problem with the FormsAuth.  How do you troubleshoot this issue?

thanks