Private Function CountDown() As String
        Try
            Dim ts As TimeSpan = New TimeSpan(0, 0, Remaining)
            If Remaining > 0 Then
                Remaining = Remaining - 1
            Else
                TimerZeit.Stop()
            End If
            Return ts.Hours.ToString("00") & ":" & ts.Minutes.ToString("00") & _
              ":" & ts.Seconds.ToString("00")
        Catch
        End Try
        Return ""
    End Function

Private Sub TimerZeit_Tick(ByVal sender As Object, ByVal e As System.EventArgs) _
  Handles TimerZeit.Tick
        NotifyIcon1.Text = CountDown()
End Sub