Private Sub txt_Validating_numeric(ByVal sender As System.Object, ByVal e As _
    System.ComponentModel.CancelEventArgs) Handles txt_PLZ.Validating
    check_Num_field(sender)
  End Sub
 
  Private Function check_Num_field(ByVal sender As Object) As Boolean
    Dim inp_ok As Boolean = False
    If Not IsNumeric(sender.Text) Then
      ErrorProvider1.SetError(sender, "Bitte geben Sie eine Zahl ein.")
      Me.txt_Message.Text = " Bitte geben Sie eine Zahl ein."
    Else
      ' Clear the error.
      ErrorProvider1.SetError(sender, "")
      Me.txt_Message.Text = " "
      inp_ok = True
    End If
    Return inp_ok
  End Function
 
  Private Sub txt_Validating(ByVal sender As System.Object, ByVal e As _
    System.ComponentModel.CancelEventArgs)
    check_Text_field(sender)
  End Sub
 
  Private Function check_Text_field(ByVal sender As Object) As Boolean
    Dim inp_ok As Boolean = False
    If sender.Text = "" Then
      ErrorProvider1.SetError(sender, "Bitte geben Sie eine Bezeichnung ein.")
      Me.txt_Message.Text = " Bitte geben Sie eine Bezeichnung ein."
    Else
      ' Clear the error.
      ErrorProvider1.SetError(sender, "")
      Me.txt_Message.Text = " "
      inp_ok = True
    End If
    Return inp_ok
  End Function

Private Sub handles_ItemDrag(ByVal sender As Object, _
           ByVal e As System.Windows.Forms.ItemDragEventArgs) Handles _
           show_GruppeB.ItemDrag, show_GruppeA.ItemDrag, _
           show_Gruppe_Detail.ItemDrag
 
    Dim myItems(9) As ListViewItem
 
    myItems(0) = New ListViewItem
    myItems(1) = New ListViewItem
    myItems(2) = New ListViewItem
 
    myItems(0).Text = sender.SelectedItems(0).Tag
    myItems(2).Text = sender.name ' Um zu unterscheiden wer sendet 
 
    sender.DoDragDrop(New DataObject("System.Windows.Forms.ListViewItem()", _
      myItems), DragDropEffects.Copy)
 
  End Sub
  Private Sub handles_DragEnter(ByVal sender As System.Object, ByVal e As _
    System.Windows.Forms.DragEventArgs) Handles show_GruppeB.DragEnter, _
    show_GruppeA.DragEnter, show_Gruppe_Detail.DragEnter
 
    If e.Data.GetDataPresent("System.Windows.Forms.ListViewItem()") Or _
      e.Data.GetDataPresent(DataFormats.Text) Then
      e.Effect = DragDropEffects.Copy
    Else
      e.Effect = DragDropEffects.None
    End If
  End Sub
 
  Private Sub handles_DragDrop(ByVal sender As System.Object, ByVal e As _
    System.Windows.Forms.DragEventArgs) Handles show_GruppeB.DragDrop, _
    show_GruppeA.DragDrop, show_Gruppe_Detail.DragDrop
    If e.Data.GetDataPresent("System.Windows.Forms.ListViewItem()") Then
      Dim sendData() As ListViewItem = e.Data.GetData( _
        "System.Windows.Forms.ListViewItem()")
      If sender.name.ToString = "show_GruppeB" And sendData(2).Text = _
      "show_GruppeA" Then
        table_handle.write_Gruppe(KontaktNI_selectedIndex, sendData(0).Text)
        refreshGruppeB()
        refreshGruppeA()
      End If
      If sender.name.ToString = "show_GruppeA" And sendData(2).Text = _
        "show_GruppeB" Then
        If table_handle.get_GruppeDetail_count(table_handle.get_Gzpj(sendData( _
        0).Text, KontaktNI_selectedIndex, "GzpjNI")) = 0 Then
          table_handle.delete_Gruppe(KontaktNI_selectedIndex, sendData(0).Text)
          refreshGruppeB()
          refreshGruppeA()
        Else
          MsgBox("Gruppe konnte nicht gelöscht werden. Es befinden sich noch" & _
            "zugordnete Dokumente darin !!", , "Control")
        End If
      End If

Sector Twelve, or to Infinity and Beyond, whichever comes first.!