Hehe Sorry! Okay, here are four screenshots. Hopefully they'll help!
1: the Category list at the beginning of my catalog. See Laurann Dohner's Mating Heat series? In actuality, there should be a book 2 in her list. I added book 2 to my Calibre, renamed the original to old and put it as book 4, and then put the info for the copied book as book 2...and book 2 doesn't show up. (the original book 4 didn't either when it was named book 2. This is just to show you that the book itself DOES show up when it's listed as book 4 in the series.)
2-4: Here are shots of what you see if you click on the first book in Laurann Dohner's Mating Heat series up in the Category list. Pic #2 is book 1. Pic #3 is book 2 (which is missing in the Category list!), Pic 4 is book 3, & Pic 5 is book 4.