private void RadCalendar1_Navigating(object sender, Telerik.WinControls.UI.CalendarNavigatingEventArgs e)
{
    var nextStartdate = new DateTime();

    var currentStartdate = this.radCalendar1.CalendarElement.CalendarVisualElement.View.ViewEndDate;

    if (e.Direction == CalendarNavigationDirection.Forward)
    {
        nextStartdate = currentStartdate.AddMonths(1);
        var montView = new MultiMonthView(this.radCalendar1, nextStartdate);
        montView.ViewStartDate = nextStartdate;
        this.radCalendar1.CalendarElement.CalendarVisualElement.View = montView;
    }

    else if (e.Direction == CalendarNavigationDirection.Backward)
    {
        nextStartdate = currentStartdate.AddMonths(-1);
        var montView = new MultiMonthView(this.radCalendar1, nextStartdate);
        montView.ViewStartDate = nextStartdate;
        this.radCalendar1.CalendarElement.CalendarVisualElement.View = montView;
    }

    e.Cancel = true;
}