ePub Version

hi, i'm an author and i have a book in epub version (no mutitouch) on ibooks store.

i have some problem to make a new version of my book.

i wrote in metadata.opf file this two lines:

prefix=”ibooks:http://vocabulary.itunes.apple.com/rdf/ibooks/vocabulary-extensions-1.0/” (in <package>)

and <meta property=”ibooks:version”>1.1</meta> (out from <package>)

the problem is that when i send everytingh to iTunes Producer i have this error:

ERROR ITMS-4172: "version_whats_new text cannot be supplied for an unversioned publication." at Book (MZItmspBookPackage)ù

WHY?!??!? tnks for your help!!!