when there is a value in my session variable my ajax calls work properly... But when a session is timedout it doesn't seem to work returning empty json result....

public JsonResult GetClients(int currentPage, int pageSize)
        {
            if (Session["userId"]!=null)
            {
                var clients = clirep.FindAllClients(Convert.ToInt32(Session["userId"])).AsQueryable();
                var count = clients.Count();
                var results = new PagedList<ClientBO>(clients, currentPage - 1, pageSize);
                var genericResult = new { Count = count, Results = results ,isRedirect=false};
                return Json(genericResult);
            }
            else
            {
                var genericResult = new {redirectUrl = Url.Action("Create", "Registration"), isRedirect = true };
                return Json(genericResult);
            }

        }

However else part does'nt seem to work....

   success: function(data) {
       alert(data.Results);
        if (data.isRedirect) {
            window.location.href = data.redirectUrl;
        }
   }

EDIT:

My global.asax has this,

public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                "Clients",                                             
                "Clients/{action}/{id}",                          
                new { controller = "Clients", action = "Index", id = "" }  
            );

            routes.MapRoute(
               "Registrations",                                              
               "{controller}/{action}/{id}",                          
               new { controller = "Registration", action = "Create", id = "" } 
           );
        }