get outlook single occurrence of recurring calendar event from double click on calendar - outlook

Question

I am creating an outlook plugin that opens a SharePoint Calendar event for editing. The SharePoint Calendar is added to outlook as an overlay.
When clicking on the series event and editing a series everything works fine. But when I select just this one (occurrence). I am unable to get any of the properties for the AppointmentItem object.
I have tried both the ReadComplete and the Open events and still get an exception:
Exception from HRESULT: 0x80040108" and I am unable to access the
Parent. It appears all of the properties are null except Class = 26
and MessageClass = "IPM.Appointment"
private void Application_ItemLoad(object item)
{
_item = item;
try
{
if (!(item is AppointmentItem) || !_exp.CurrentFolder.Name.Contains("Test - Conference Room ")) return;
_warnUser = true;
_apptItem = (AppointmentItem) item;
_apptItem.ReadComplete += test;
_apptItem.Open += McAI_Open;
}
catch (Exception ex)
{
var expMessage = ex.Message;
MessageBox.Show(expMessage);
}
}
private static void ThisAddIn_Shutdown(object sender, EventArgs e)
{
// Note: Outlook no longer raises this event. If you have code that
// must run when Outlook shuts down, see https://go.microsoft.com/fwlink/?LinkId=506785
}
private void McAI_Open(ref bool cancel)
{
_warnUser = false;
var conferenceRoom = _exp.CurrentFolder.Name;
conferenceRoom = conferenceRoom.Replace("Test - ", "");
if (!(_item is AppointmentItem)){return;}
try
{
var g = _apptItem.IsRecurring;
if (_apptItem != null && _exp.CurrentFolder.Name.Contains("Test") && _apptItem.Location != null)
{
var location = _apptItem.Location;
var result = location.Substring(location.LastIndexOf(':') + 1);
cancel = true;
var sharePointItemId = int.Parse(result);
var frm = new FrmCalendarSelection(
"<SharePointURL>" + conferenceRoom,
sharePointItemId);
frm.Show();
frm.Closed += Frm_Closed;
}
else if (_apptItem != null && _exp.CurrentFolder.Name.Contains("Test") && _apptItem.Location == null)
{
cancel = true;
var frm = new FrmCalendarSelection(
"<SharePointURL>" + conferenceRoom);
frm.Show();
frm.Closed += Frm_Closed;
}
}
catch (Exception e)
{
throw e;
}
}