Sometimes during the working an exception occurs in week view, when we drag some appointment or just click on appointmetn object.

Stack trace is given below.

"   at Infragistics.Win.UltraWinSchedule.ScheduleDrawUtility.SetDayHeaderAppearancePropertyDefaultValuesOffice2007(Outlook2007ColorScheme colorScheme, Boolean isToday, Boolean isHotTracking, AppearanceData& defaultAppData)\r\n   at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingle.ResolveDayHeaderAppearance(DateTime date, AppearanceData& appData, AppearancePropFlags& requestedProps, Owner owner, Boolean isHotTracking)\r\n   at Infragistics.Win.UltraWinSchedule.MonthViewSingle.DayNumberUIElement.InitAppearance(AppearanceData& appearance, AppearancePropFlags& requestedProps)\r\n   at Infragistics.Win.UltraWinSchedule.MonthViewSingle.DayNumberUIElement.AddChildUIElements(UIElementsCollection oldElements)\r\n   at Infragistics.Win.UltraWinSchedule.MonthViewSingle.DayNumberUIElement.PositionChildElements()\r\n   at Infragistics.Win.UIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)\r\n   at Infragistics.Win.UIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)\r\n   at Infragistics.Win.UIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)\r\n   at Infragistics.Win.UIElement.VerifyChildElements(Boolean recursive)\r\n   at Infragistics.Win.UIElement.VerifyChildElements()\r\n   at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingle.OnSelectedActivitiesChanged(SelectedActivitiesCollectionBase selectedActivities)\r\n   at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingleBase.OnCalendarInfoChanged(CalendarInfoChangedEventArgs args)\r\n   at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingle.OnCalendarInfoChanged(CalendarInfoChangedEventArgs args)\r\n   at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingleBase.OnCalendarInfoChanged(Object sender, CalendarInfoChangedEventArgs args)\r\n   at Infragistics.Win.UltraWinSchedule.CalendarInfoChangedEventHandler.Invoke(Object sender, CalendarInfoChangedEventArgs e)\r\n   at Infragistics.Win.UltraWinSchedule.UltraCalendarInfo.OnCalendarInfoChanged(CalendarInfoChangedEventArgs e)\r\n   at Infragistics.Win.UltraWinSchedule.UltraCalendarInfo.FireCalendarInfoChangedEventHelper(PropChangeInfo propChangeInfo, PropertyIds propId)\r\n   at Infragistics.Win.UltraWinSchedule.UltraCalendarInfo.OnSubObjectPropChanged(PropChangeInfo propChangeInfo)\r\n   at Infragistics.Shared.SubObjectBase.NotifyPropChange(PropChangeInfo trigger)\r\n   at Infragistics.Shared.SubObjectBase.NotifyPropChange(Enum propId)\r\n   at Infragistics.Win.UltraWinSchedule.SelectedActivitiesCollectionBase.ContentsChangedHelper(ContentsChangeType contentsChangeType, SubObjectBase[ activities, Boolean clearExisting)\r\n   at Infragistics.Win.UltraWinSchedule.SelectedActivitiesCollectionBase.AddHelper(SubObjectBase[ activities, Boolean clearExisting)\r\n   at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingleBase.Infragistics.Win.ISelectionManager.SelectItem(ISelectableItem item, Boolean clearExistingSelection)\r\n   at Infragistics.Win.SelectionStrategyExtended.OnMouseDown(ISelectableItem item, MouseMessageInfo& msginfo, Boolean forceDrag)\r\n   at Infragistics.Win.SelectionStrategyExtendedAutoDrag.OnMouseDown(ISelectableItem item, MouseMessageInfo& msginfo)\r\n   at Infragistics.Win.SelectionStrategyExtended.OnMouseMessage(ISelectableItem item, MouseMessageInfo& msginfo)\r\n   at Infragistics.Win.ControlUIElementBase.ProcessMouseDownHelper(Object sender, MouseEventArgs e)\r\n   at Infragistics.Win.ControlUIElementBase.ProcessMouseDown(Object sender, MouseEventArgs e)\r\n   at Infragistics.Win.Utilities.ProcessEvent(Control control, ProcessEvent eventToProcess, EventArgs e)\r\n   at Infragistics.Win.UltraControlBase.OnMouseDown(MouseEventArgs e)\r\n   at Infragistics.Win.UltraWinSchedule.UltraMonthViewSingleBase.OnMouseDown(MouseEventArgs e)\r\n   at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks)\r\n   at System.Windows.Forms.Control.WndProc(Message& m)\r\n   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)\r\n   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)\r\n   at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)\r\n   at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)\r\n   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)\r\n   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)\r\n   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)\r\n   at System.Windows.Forms.Application.Run()\r\n   at Coronado.Framework.PFM.Program.Main() in C:\\Coronado Versions\\BetaRelease1700\\desktop\\Framework\\PFM\\Program.cs:line 79\r\n   at System.AppDomain.nExecuteAssembly(Assembly assembly, String[ args)\r\n   at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[ args)\r\n   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()\r\n   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)\r\n   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)\r\n   at System.Threading.ThreadHelper.ThreadStart()" 

DeclaringType:  {Name = "ScheduleDrawUtility" FullName = "Infragistics.Win.UltraWinSchedule.ScheduleDrawUtility"} 

How to handle this exception. Kindly help.