Extracting files from Portfolio - problem with outlook email created portfolios

Currently I have developed a plugin that can extract files from portfolios using:-

PDNameTree tree = PDDocGetNameTree(pdDoc, ASAtomFromString("EmbeddedFiles"));

and

PDFileAttachmentFromCosObj

But i've noticed with Outlook email created portfolios the above is PDNameTree invalid.  any suggestions?   is it under another atom string or something?

Thanks,

Lee.