Hi Gary,
I must admit, I hadn't actually tested the advice given there but, now that I have, I think it was wrong and that the simple answer is that you can't select more than one item in a dropdown formfield. If you need to allow items to be combined, you'll have to combine them as alternate selections in the dropdown formfield or use multiple such formfields, each containing an appropriate set of selections. For example, if the options are prioritised, you might have all the options in the 1st dropdown, then only the remining lower-level items in the 2nd - which would be populated via vba based on the selection in the 1st dropdown.