Hi , it seems to work for me have a look at my Global.asax.cs: 

public class Global : System.Web.HttpApplication
{
    private static MetaModel s_defaultModel = new MetaModel();
    public static MetaModel DefaultModel
    {
        get { return s_defaultModel; }
    }


    public static void RegisterRoutes(RouteCollection routes)
    {
        EntityConnectionStringBuilder entityBuilder = new EntityConnectionStringBuilder();
        entityBuilder.Provider = "System.Data.SqlClient";
        entityBuilder.ProviderConnectionString = "server=aragorn;database=Northwind;Integrated Security=SSPI;MultipleActiveResultSets=True";
        entityBuilder.Metadata = @"res://*";
        var objContext = new NorthwindContext.NorthwindEntities(entityBuilder.ToString());


        DefaultModel.RegisterContext(() => new NorthwindContext.NorthwindEntities(entityBuilder.ToString()),
                    new ContextConfiguration()
                    {
                        ScaffoldAllTables = true
                    });




        routes.Add(new DynamicDataRoute("{table}/{action}.aspx")
        {
            Constraints = new RouteValueDictionary(new { action = "List|Details|Edit|Insert" }),
            Model = DefaultModel
        });
    }


    void Application_Start(object sender, EventArgs e)
    {
        RegisterRoutes(RouteTable.Routes);
    }
}

Note that I tried it in an DD4 Web Application Project.