Many WordPress themes, even WordPress default themes, use post_class on all content, including pages. WordPress pages, as opposed to posts, don’t usually include a date and author because pages are not date based. Google’s Structured Data Testing Tool sees the hentry class and expects to see date and author, so it lists errors.
Solution: Remove WordPress hentry Class from Pages.
Question: where should I add the coding lines in WeaverII-pro? Advanced options/<head>section/Actions and filters?