I found this topic in the archive (September) but it applies , slightly differently, to my problem.
I have downloaded 2 art books into Digital Editions, and they seem to be fine, except that there are some images and tables missing (I checked this by comparing to the "read online" selection in eBooks). The images are reproductions of artworks, sketches, diagrams, and tables. Most of these are present, just some are not! The message on the info says "some PDF formats are not supported" (I guess JPEG.2000)- which seems strange when most of the images download properly - it would be unusual for a publication to be internally inconsistent with this.
I bought the books from eBooks.com, and they are part of a series of art books designed for art students: "Virtual Art Academy Master Program".
I have downloaded Adobe Reader 7 as the link instructed, re-downloaded and the same images are missing. I would be surprised if the images etc were using differing formats throughout the book? Which is why it's a puzzle that only some are missing.