On an iPad? That should be all but impossible. I suppose it 'might' happen if you restored a backup from a newer iPad to an iPad with an older version of iOS. Can't think of any other way to do it.
On a Mac or Windows computer, it sounds like you've somehow installed a version of iTunes that is older than the music library. Or restored a newer iTunes library to an older computer. Go to Apple.com and install he newest version of iTunes.