private void Berechne(Finanzierung fina)
        {
            try
            {
                this.OriginalFina = (Finanzierung)fina.Clone();

                Tilgungsplan.BerechneTilgungsplanFesteAnnuitaet(fina);
                this.CurrentPlot = new LinePlot(fina);
            }
            catch (Exception ex)
            {

                TaskDialogOptions tdo = new TaskDialogOptions();
                tdo.MainIcon = VistaTaskDialogIcon.Warning;
                tdo.MainInstruction = ex.Message;
                tdo.Owner = App.window;
                tdo.CommonButtons = TaskDialogCommonButtons.Close;

                TaskDialogInterop.TaskDialog.Show(tdo);
            }
        }