How To Refresh WPF Gantt Schedule

  …
        <gantt:GanttControl x:Name="Gantt"
                            ItemsSource="{Binding TaskDetails}"
                            CustomScheduleSource="{Binding CustomScheduleSource}"
                            ScheduleType="CustomDateTime"
                            VisualStyle="Metro">
        </gantt:GanttControl>

         …

            <Slider Grid.Row="1"
                    Minimum="20"
                    Maximum="100"
                    Value="20"
                    ValueChanged="Slider_ValueChanged" />

         …

    …

        private void Slider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
        {
            (this.DataContext as ViewModel).CustomScheduleSource[1].PixelsPerUnit = (sender as Slider).Value;
            this.RefreshSchedule();
        }

        private void RefreshSchedule()
        {

            FieldInfo propertyInfo = typeof(GanttControl).GetField(
                                                              "GanttSchedule",
                                                              BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);

            GanttSchedule ganttSchedule = (GanttSchedule)propertyInfo.GetValue(this.Gantt);
            if (ganttSchedule != null)
            {
                MethodInfo RedrawSchedule = ganttSchedule.GetType().GetMethod("RedrawSchedule", BindingFlags.Instance | BindingFlags.NonPublic);
                RedrawSchedule.Invoke(ganttSchedule, new object[] { });
            }
        }