问未激发SqlTableDependency onchange事件

EN

 string conn = @"data source=secret server; integrated security=True; initial catalog=secret db;User id=secret user";

    var mapper = new ModelToTableMapper<SqlDataModel>();

    mapper.AddMapping(c => c.datavalue, "datavalue");       

    using (var dep = new SqlTableDependency<SqlDataModel>(conn, "data", mapper))
    {
        dep.OnChanged +=  Changed;
        dep.OnStatusChanged += OnStatusChanged;
        dep.OnError += OnError;
        dep.TraceLevel = TraceLevel.Verbose;
        dep.TraceListener = new TextWriterTraceListener(Console.Out);            
        dep.Start();          

        Console.WriteLine("Press a key to exit");           
        Console.ReadKey();            
        dep.Stop();
    }
}
static void OnStatusChanged(object sender, StatusChangedEventArgs e)
{
    Console.WriteLine(e.ToString());
}
static void OnError(object sender, ErrorEventArgs e)
{
    Console.WriteLine(e.ToString());
}
static void Changed(object sender, RecordChangedEventArgs<SqlDataModel> e)
{      
    if (e.ChangeType != ChangeType.None)
    {
        var changedEntity = e.Entity;
        Console.WriteLine("DML operation: " + e.ChangeType);          
        Console.WriteLine("value: " + changedEntity.datavalue);
    }
}