Hi, Abbey,

Text boxes aren't regular text, they're actually considered graphics
that float in the drawing layer. For that reason, things like index
entries and table of contents entries that are in text boxes are
"invisible" to the INDEX and TOC fields.

If you need something like a text box but in the text layer, so it
accepts index and TOC entries, you need a frame. If you already have a
text box, select it and go to Format Text Box, then click the Text Box
tab, and click the Convert to Frame button.

--
Regards,
Jay Freedman
Microsoft Word MVP        FAQ: http://www.mvps.org/word