Forms 6i OLE2 Outlook problem with getshareddefaultfolder

I've been using OLE2 to do Forms/Outlook integration for many years successfully, but I've recently run across a problem I haven't seen before. I need to open a delegate's calendar, so I found the GetSharedDefaultFolder to replace the normal GetDefaultFolder function I use to open a personal (using parameter 9) or public (using parameter 18) calendar.

GetSharedDefaultFolder requires two arguments: the recipient folder object (which I successfully get using the CreateRecipient and Resolve functions), and the folder type (again 9, for calendar). However, when I add these two arguments and attempt to use the GetDefaultSharedFolder function, I keep getting the dreaded ORA-305500 error.