Problem with upload book.epub maybe font?

Hi, i have problem with upload my new book to the ibooks because i get this:

ERROR ITMS-9000: "sample.epub: resource OPS/Fonts/EmbedFont.ttf is missing (For more information refer to iBooks: Use EpubCheck to validate your EPUB books" at Book (MZltmspBookPackage)

I dont know, what should i do to repair it 😟 Maybe it is problem with font, becasue i use american typewriter? I converted book from Pages.app to pdf after that i converted pdf to ePub and i wanted to upload it....

Thank for help 🙂