Fixing TOC in Calibre

[Bran200]

Please bear with me as I'm new to posting and also not computer/html literate.

Having uploaded my ebook to calibre, I've been able to make some of the edits I needed to make.

There are problems with my TOC, however, which I can't figure out how to fix. Viewing my ebook TOC on a kindle viewer revealed two things, One: Unlike how all the chapter headings are in blue and underlined, one chapter heading is black and not underlined. This link doesn't work. Two: All other chapter links work, but pressing each one does not send you to the chapter....it sends you to the end of the chapter before it.

In the calibre html box, I noticed the faulty chapter link lacks some of the code all the others have. I inserted that code, which made it blue and underlined, but the link still didn't work (it still didn't send me to the location in the book).

Something else I noticed...In the code, all the chapters have a number (split_005...006...007etc.) showing the sequence of the chapters. Here's the thing....the chapter before the one with the faulty link is numbered 043, and the chapter after the one with the faulty link is numbered 046. That's right. It skips two. The code to the faulty link has no number. I tried entering 044, but this didn't fix anything.

I'm at a loss for what to do. Can any one help? Thank you very much.