Not sure what happened. When I first tried it I got the same error message on the same line. That came up a few times afterwards, after trying a few little things like making sure the document was saved, etc.

Then, I noticed one time that despite the error message, it seemed to have worked! So, I restarted the mail merge process again, created a new document, and ran the script through. No run time error! I have no idea why it went away, but it seems to be working!

Many thanks Greg.