I downloaded a sample of a book from the iBooks store and decided I wanted to get the full book. The sample was actually kinda wimpy - 10 pages but most were the extraneous pages (e.g. title page). I downloaded the full book by clicking on the purchase button that appears within the sample. But what I got is only 18 pages long! And it's a bit messed up. So I tried deleting the book from my iPad and then re-downloaded it. Same thing. Only 18 pages. This was my first book purchase. What do I do?