Private Sub txt_Validating(ByVal sender As Object, ByVal e As _
  System.ComponentModel.CancelEventArgs) Handles ArtiIDTextBox.Validating
 
        Dim myTxt As TextBox
 
        Try
            ' Konvertieren in eine Textbox (muss Textbox sein)
            myTxt = sender
 
            ' Wenn das Textfeld leer ist, auf Nothing setzen
            If myTxt.Text.Trim = "" Then
                myTxt.Text = Nothing
            End If
 
 
        Catch ex As Exception
            MessageBox.Show("Fehler")
        End Try
 
    End Sub