audiobooks sync

I have 169 audiobooks in iTunes, 40 of them are checked/ticked. When I plug in my 2 iPhones and choose sync all audiobooks it shows just the 40 books. However when I try to do the same with my ipad it shows all 169 books (including all the unchecked ones). This takes me way over my ipads memory. Is this a bug or am I doing something wrong.