epub validation error -- image not reachable
I have created a book using InDesign that is using a jpg image for its cover, which I can pick in InDesign before creating the epub. When I load the epub in Sigil and validate it I get this error:
OEBPS/Images/cover.jpg not available This resource is present in the OPF <manifest>, but it's not reachable (it's unused).
This book will be for Amazon, so I convert it to mobi with Calibre and open it with the Kindle Previewer. The cover seems fine to me. I also have placed this same jpg on the first page of the book, perhaps that's an issue. The cover.jpg is indeed within the epub file.
In any case, I don't know whether I have a problem on my hands or whether I should just ignore this and submit the book to the Amazon store.
Thanks for all comments