i put on four books through the usb cord. all four are valid. but only 3 appear on the list. the fourth one appears as an icon before i go to books (some kind of recently added something?) but in the book section it doesn't appear. when i click on the icon the book loads fine. but it won't be there for long so that's not a valid way to access it. i tried moving it to the document section and it lists there and loads fine. so i can read it but it's a pain in the butt to have books in two different sections. and yes it's in mobi format.