Books not showing up after sync in iBooks (iPad and iPhone 4)

OK I had this problem for so long and I just figured it out!!! My books were hidden for some reason, not sure why but maybe your's is too!! I hope this helps...

Make sure you sync with iTunes before this as mention in some of the replies below and make sure your iTunes account on both devices are matched to the same account

1. go on your mac and open the application ibooks

2. click 'iBook store' in the upper left hand corner

3. On the right side of the 'featured' page, there will be a little column

4. Under the sub category, 'quick links' select account

5. You should come to a page called 'account information'

6. scroll down to find the sub category, 'iTunes in the cloud'

7. find the 'hidden purchases' category and select 'manage' to the right

8. from there you can select the books you need

9. Go to your iPad or other device

10. find the little bar on the bottom of your page and select 'purchased' then 'books'

11. select the 'all' button and you can download your books

Good Luck!!

I been having a roughly the same problem. Since the last update my Mac laptop and iPad 4 iBooks don't sync. I add books to the Mac iBooks but they don't show up on the iPad. if I get a book on the iPad it does appear on the Mac. I tried signing in and out, truning on and off the sync buttons, and horrors of horrors I deleted books from the Mac and it did remove them from the iPad.