recalling a created calendar event in Entourage from Filemaker

I’ve created a calendar event in Entourage from Filemaker. I’d like to send the event ID back to filemaker so that I can use it to later recall the calendar item in entourage. But when I try to set the field in Filemaker to newEvent (which is the variable for the Event ID), I get the following error message:

Can’t make «class cEvt» id 1730 of application “Microsoft Entourage” into the expected type.

If I try to coerce to become a text string I get this message:

Can’t make «class cEvt» id 1730 of application “Microsoft Entourage” into type string.

Any ideas?