unwind-protect&choose-file-dia

[KHOSLA@AppleLink.Apple.COM (Khosla Consulting, Ashok Khosla,PAS)]

I'm having trouble getting the choose-file-dialog to work correctly when
cancelled - Here is a sample:
 
(progn (setf aFileName "Unnamed")
           (setf aFileName (unwind-protect
                             (choose-file-dialog :mac-file-type :|TEXT|)
                             "cancelled"))
           aFileName)
 
When the SFGetFile appears, if I hit escape or cancel, the dialog unwinds past
my unwind protect, and I never get aFileName set to "cancelled".
 
 
Any ideas?