Show in Textbox actual number of records from SQL Database - VB.net

Hi,

I'm trying to use notification from SQL database to count actual records in table. I need this in real-time, because I would like to create InstantMessage popup informing particular employee about message for him in the database.

On SQL I enabled broker,

And on WPF window I'm using this code:

Private Function DoesUserHavePermission() As Boolean
        Try
            Dim clientPermission As SqlClientPermission = New SqlClientPermission(Security.Permissions.PermissionState.Unrestricted)
            clientPermission.Demand()
            Return True
        Catch ex As Exception
            Return False
        End Try
        Return True
    End Function
    Public Sub GetNames()
        If Not DoesUserHavePermission() Then
            Return
        End If
        Dim enu As String = txtEmplID.Text
        'lbNames.Items.Clear()

        ' You must stop the dependency before starting a new one.
        ' You must start the dependency when creating a new one.
        SqlDependency.Stop("Data Source=c0040513.itcs.hp.com,443\SQLSERVER;User ID=Admonistrator;Password=Kakademona666;Initial Catalog=Prometheus")
        SqlDependency.Start("Data Source=c0040513.itcs.hp.com,443\SQLSERVER;User ID=Admonistrator;Password=Kakademona666;Initial Catalog=Prometheus")

        Using cn As SqlConnection = New SqlConnection("Data Source=c0040513.itcs.hp.com,443\SQLSERVER;User ID=Admonistrator;Password=Kakademona666;Initial Catalog=Prometheus")

            Using cmd As SqlCommand = cn.CreateCommand()

                cmd.CommandType = CommandType.Text
                cmd.CommandText = "SELECT COUNT([ID]) FROM dbo.tbl_InstantMessage where Enumber = '" & enu & "'"

                cmd.Notification = Nothing

                ' creates a new dependency for the SqlCommand
                Dim dep As SqlDependency = New SqlDependency(cmd)
                ' creates an event handler for the notification of data changes in the database
                AddHandler dep.OnChange, AddressOf dep_onchange

                cn.Open()

                Dim result As Integer = Convert.ToInt32(cmd.ExecuteScalar)
                btnNewMessage.Text= result

            End Using

        End Using
    End Sub
    Private Sub dep_onchange(ByVal sender As System.Object, ByVal e As System.Data.SqlClient.SqlNotificationEventArgs)

        If btnNewMessage.Dispatcher.CheckAccess Then

            btnNewMessage.Dispatcher.BeginInvoke(New Action(AddressOf GetNames))

        Else
            GetNames()
        End If
        Dim dep As SqlDependency = DirectCast(sender, SqlDependency)
        RemoveHandler dep.OnChange, AddressOf dep_onchange

    End Sub

And I'm calling it on Window_Loaded. 

When I turn on my app - it's working, but if I make some amendments in the database, it's not refreshing textbox.

Thank you in advance

Mathh