How to retrieve an appointment item using GlobalAppointmentID

I'm developing a sync application for outlook 2007 using VS2005 and
VSTO-SE

I'm trying to find a way to search for an appointment using the
GlobalAppointmentID property

Tried using the find method on the calendar folder object like this:
calendarFolder.Items.Find("[GlobalAppointmentID] = 'IDSTRING'");
But that resulted in an exception ("Condition is not valid."),
probably because the GlobalAppointmentID is a binary property, and as
such cannot be used to filter items (can anyone confirm that ?).

Help and Ideas would be appreciated.