Some alert messages in iBooks include the phrase "text not allowed." For example, you might see "ERROR ITMS-9000: 'FileName.html(16): text not allowed here.'"
You can include text only in certain elements of an ePub, such as the paragraph element (<p>) or header element (<h1>). You might also see this error if you use the blockquote (<blockquote>) element in the book’s metadata.
Go to the iBooks Asset Guide in Resources and Help in iTunes Connect to learn how to code using ePub best practices.