Cannot read one instance of this recurring appointment

Hi,

I'm trying to catch the event that new exceptions have
been created for recurring meetings from a COM Add-in.

I've defined an "ItemChange" event on the calendar folder.
Then I loop on the recurrence exceptions and I try to get
the Appointment item associated with each exception.

The problem is that sometimes Outlook displays an error
message to the End user saying "Cannot read one instance
of this recurring appointment. Close any open appointments
and try again, or recreate the appointment".

This happens for instance when I move one instance of the
recurring meeting in the calendar.

This reproduces in my COM Add-in as well as with VBA.

The code for the event handler is quite simple:

Private Sub colAppItems_ItemChange(ByVal item As Object)
Dim appitem As Outlook.AppointmentItem
Set appitem = item
Dim rec As Outlook.RecurrencePattern
Set rec = appitem.GetRecurrencePattern
Dim exception As Outlook.exception
For Each exception In rec.Exceptions
Dim subitem As Outlook.AppointmentItem
Set subitem = exception.AppointmentItem 'error message
Next
End Sub


Is that a known issue?

Thanks,

- Reginald