RouteData.Values null redirect

Question

I want to redirect to the main page if the incoming value is unknown or empty. But I did not succeed.

  if(RouteData.Values["lab"] ==null )
    {
        Response.Redirect("/Default");
    }

Answer 1

This is what I did to redirect to my error page, via the controller, when authenticating LDAP groups:

var routeData = new RouteData();
                    routeData.Values.Add("message", errorModel.message);
                    routeData.Values.Add("action", "Index");
                    routeData.Values.Add("controller", "ErrorPage");
                    IController ctrl = new ErrorController();
                    ctrl.Execute(new RequestContext(new HttpContextWrapper(Context), routeData));
Response.End();