Well, I didn’t notice I used the wrong ISBN number when I got my barcode for the back of the book. Hell, I didn’t even notice it till I got my second proof (the first was cut poorly). I’d assigned that ISBN to an ebook at Smashwords so couldn’t change it, and you can’t use the ISBN for two different titles.
After trying to get Ingram to make the changes in their metadata and uploading the corrected book cover twice (only to have tech support changing it so the proof showed the old barcode, both times, the bastards) I had to dump the initial upload of the book and resubmit.
Fortunately, I had a code that let me submit for free, but I’m pissed as hell at myself for being so goddamned stupid. And lazy. If I’d updated my list of ISBNs bought and assigned when I should have, I never would have thought the number was available.
It’s updated now, baby.