Signalr SinglR通知不显示MVC

我正在训练如何在数据库发生更改时发送通知，但什么也没发生我刚刚启动了他的控制台浏览器通知中心

NotificationHub.cs

 public class NotificationHub : Hub
{
    //public void Hello()
    //{
    //    Clients.All.hello();
    //}
}

NotificationComponent.cs

       void sqlDep_OnChange(object sender, SqlNotificationEventArgs e)
    {

        if (e.Type == SqlNotificationType.Change)
        {
            SqlDependency sqlDep = sender as SqlDependency;
            sqlDep.OnChange -= sqlDep_OnChange;


            var notificationHub = GlobalHost.ConnectionManager.GetHubContext<NotificationHub>();
            notificationHub.Clients.All.notify("added");

            RegisterNotification(DateTime.Now);
        }
    }

    public List<Activity> GetContacts(DateTime afterDate)
    {
        using (DataBaseTabelModel dc = new DataBaseTabelModel())
        {
            return dc.Activities.Where(a => a.Date > afterDate).OrderByDescending(a => a.Date).ToList();
        }
    }

 var notificationHub = $.connection.notificationHub;
        $.connection.hub.start().done(function () {
            console.log('Notification hub started');
        });

        notificationHub.client.notify = function (message) {
            if (message && message.toLowerCase() == "added") {
                updateNotificationCount();
            }
        }