Saving Word file to PDF

Hi everyone.
My vb6 application uses a command button to open a Word 2010 document and fill it with various data. What I would like to do is place another button to convert this document into a pdf file. I wrote code that opens and tries to save (using the SaveAs2 method) this document but I get an error 4198 Command failed message.
Anyone able to shed light?

Thanks

Tim Christopher