Can you find an element with id="filepos91308" in "OEBPS/Text/visionepub_split_012.html"? If you can, then that's a bug in epubcheck. You should report it on their tracker.
If you can't find the ID, then that's a problem with your epub. Make sure the anchor you're linking to is using an "id" attribute instead of a "name" one.
|