iBooks Add Cover

We have a short demo project and we need to swap out the cover. Dragging and dropping a new cover appears to work, but then in Preview or Export, the old cover shows up. As I recall, there was a different way that we added the cover last time. This should take an experience iBooks person about 2 minutes, so we expect bids in the $25 range. Then, if the publisher accepts the proposal, we would have a much larger project for the whole book.