They must be public pages – not private and not drafts.
Public – The page will be visible to everyone.
Protected – The page is protected with a password you set. Only people who have the password can view a protected page.
Private – Pages are only visible to blog Editors and Administrators. Private pages are not visible in Reader, feeds, or in any search. A page can be private without being password protected. http://en.support.wordpress.com/pages/page-visibility/