Thank you! Yes, you are correct: I had the wrong XPath. (sigh, ignorance is not bliss...)
I've corrected it and now receive an error message that "InfoPath cannot execute any view-related object model calls. The view is not ready."
I had the same results when I instead tried to hardcode the value in the export statement.
When I try to isolate the issue, it seems it's occurring at:
Me.CurrentView.Export(myFIELDVALUE, ExportFormat.Pdf)
Thanks for your help so far - if you have any further suggestions, please let me know.
Thank you, again!