Microdata and schema.org

When I try to add schema.org microdata to the text of my HighEnd WP templated pages and posts, it does not hold, i.e. when I look back again at the text view, the itemscope and itemtype data is gone. Why will it not save?

I have not edited the template files but do see the http://schema.org/WebPage setup in those files. Are there edits that need to be done to those files to make microdata work?

I am using the visual composer on my pages.

Any advice on how to effectively add microdata to my site would be appreciated.

Thanks!