My books are not showing for keyword

I have about 15 books all dealing with OCD. Only 3 of them show up for keyword OCD. I am using Ibooks author. They all how up when I look it up on computer, just not on iphone or ipad. Not sure what could be causing this. Please help. My name is Ali Greymond, I am attaching the link for one of my books, if you click related you can see all of them.

http://itunes.apple.com/us/book/id1105447270