DoddleReport with MVC Areas

AdminAreaRegistration.cs

using System.Web.Mvc;
using DoddleReport.Web;

namespace Product.Web.Areas.Admin
{
   public class AdminAreaRegistration : AreaRegistration
   {
      public override string AreaName
      {
         get { return "Admin"; }
      }

      public override void RegisterArea(AreaRegistrationContext context)
      {
         // Any idea why this doesn't work...
         context.MapReportingRoute();

         // ...but this, effectively identical call, does?
         context.MapRoute("Admin_DoddleReport", "Admin/{controller}/{action}.{extension}/{*pathInfo}", null, new { extension = new ReportRouteConstraint() });

         // (This is the default route for this area.)
         context.MapRoute("Admin_default", "Admin/{controller}/{action}/{id}", new { action = "Index", controller = "Home", id = UrlParameter.Optional });
      }
   }
}