SqlDependency Query Notification error

Question

I'm trying to get Query Notifications working on SQL Server 2012. I was following the tutorial at this link: http://www.codeproject.com/Articles/144344/Query-Notification-using-SqlDependency-and-SqlCach

What I end up with is the OnChange event getting constantly fired. The SqlNotificationEventArgs says Info=Invalid, Source=Statement, Type=Subscribe.

From my research, I see it's having problems subscribing, but I can't figure out why. In the SQL Server event logs, all I get is

The query notification dialog on conversation handle '{D30D3675-9A2F-E311-A141-8851FB594FAA}.' closed due to the following error: 
'<?xml version="1.0"?><Error xmlns="http://schemas.microsoft.com/SQL/ServiceBroker/Error"><Code>-8470</Code><Description>Remote service has been dropped.</Description></Error>'.

I've stepped through the common concerns, like making sure I'm using a two part table name, and that my query isn't doing anything forbidden. Here's the code that sets up the event:

 public DataTable RegisterDependency()
 {
     this.CurrentCommand = 
           new SqlCommand("Select CategoryID,CategoryName,Description from dbo.[Categories]", this.CurrentConnection);

     this.CurrentCommand.Notification = null;


     SqlDependency dependency = new SqlDependency(this.CurrentCommand);
     dependency.OnChange += this.dependency_OnChange;

     if (this.CurrentConnection.State == ConnectionState.Closed)
         this.CurrentConnection.Open();

         try
         {
             DataTable dt = new DataTable();
             dt.Load(this.CurrentCommand.ExecuteReader(CommandBehavior.CloseConnection));
             return dt;
         }
         catch { return null; }

}

I'm at a loss as to what to check next. Any help is appreciated.

Answer 1

Turns out the issue was with the table definition. The column "Description" is an 'ntext' type and that doesn't work with notifications.

Answer 2

For future readers.

Closed event notification conversation endpoint with handle '{ABC123}', due to the following error: '<?xml version="1.0"?><Error xmlns="http://schemas.microsoft.com/SQL/ServiceBroker/Error"><Code>-8470</Code><Description>Remote service has been dropped.</Description></Error>'.

I got this error when my <NotificationService><ConnectionString> did not match my <ApplicationService><OnNotification> database connection values. (A small typo, but enough to throw it off)