Thanks for the continued help;

This has helped me a lot actually, as I believe that Note 3 in the original guide may not have been followed correctly (at least in my code, I can't say for the OP's).

One of the things I was trying to do was use a text and field combination for the filenames, and I couldn't get that to work. I've now just added the field for filename in the data source and that seems to work fine.

Thank you!