"Access denied" error when attempting to open documents in Acrobat via interapplication communicatio

I've been trying to open a PDF in Acrobat via interapplication communication, by using the .Open() method of an AVDoc object created from the .GetAVDoc() method of an App object (after using .Close() to close a document that was previously open in the same AVDoc object). However, when I attempt to do this, Acrobat produces an "access denied" message. I am able to open the document directly from Acrobat without problem, and via the .Open() method of an AVDoc object created by Dispatch("AcroExch.AVDoc"), but I want to use a menu command on a large number of documents, so I need to automatically open documents attatched to an App object. The problem occurs with all PDFs.