.GetDocumentHeight Script is acting silly

I'm trying to get my script to enlarge the paper size by three px on each edge, and I'm using .GetDocumentHeight and .GetDocumentWidth to do it. The problem is, regardless of what document I have open, the script thinks it's 2px x 2 px. Here's the sample script I'm trying to debug:

WITHOBJECT "CorelPHOTOPAINT.Automation.14"
 doc_height = .GetDocumentHeight() + 6
 doc_width = .GetDocumentWidth() + 6
 .ImagePapersize doc_width, doc_height, 3, -3, 8, 1, 0, 0, 0
END WITHOBJECT

Every time, it makes the resulting image 8 x 8. Any idea how to make this work?

Thanks,

Russ