Public Sub uebernameDurchClientFired(ByVal sender As Object, ByVal e As _
    System.Timers.ElapsedEventArgs)
        uebernameDurchClient.Enabled = False
        Dim client As UserConnection
        Dim entry As DictionaryEntry
        For Each entry In clients
            client = CType(entry.Value, UserConnection)
            client.SendData("ZUSPAET|")
            clients.Remove(client.Name)
        Next
           listener.Stop()
.....