way to discourage footnotes

So, here I am, trying to add a footnote to my Word document (I know, I know, there's my first mistake; I do usually use LaTeX, but...) when I get the following error message:

 

So, just precisely what is wrong with my "Start at"¹ value?  (Aside: I'm encouraged that I can have over 16 thousand numbered footnotes; I'm sure that will come in useful one of these days.  Or I would be encouraged, if I could get even the first one added.  But then I think, why shouldn't I be able to have a footnote numbered 0, or -42?) 

Anyway.  Maybe by "between", they mean "and not equal to"? Probably not, but let's try anyway, just in case:

Gah!  Oh well, I only need one footnote.  Rather than spend time figuring out what it really wants, I'll change the format, and use a custom mark instead:

Aaaaargh!!!!

---

¹ Note the different capitalisation of the "at" in the dialog box and error message.  Sloppy.^2
2 Also, note the easy use of footnotes in this post.