Setting SaveSentMessageFolder in Outllook

I am trying to set the SaveSentMessageFolder for a MailItem.  I get the the
OleSysError "An operation failed. An object could not be found."  The
problem is in the line that sets the folder.  The one I want is called
'TestFolder", and it is directly under the root, which is called "Outlook
Today - [Mailbox Smith, Paul]".  Can someone please help me with this?
Thanks.

var
  appOutlook, miMail, onMAPI, ofcFolders, ofSavefolder: variant;

begin
  appOutlook := CreateOLEObject('Outlook.Application');
  OnMAPI := appOutlook.GetNamespace('MAPI');
  ofcFolders := OnMAPI.Folders;
  ofSaveFolder := ofcFolders.Item('Test Folder');  {This is the broken line;
"ofcFolders('TestFolder)" doesn't work, either}
  miMail := appOutlook.CreateItem(0);
  miMail.SaveSentMessageFolder := ofSaveFolder;
  miMail.Display;
end;