[Plugin: WordPress SEO by Yoast] og:type problem in facebook like button

Hello i get this problem in my site when i try to click facebook like button

Object at URL
http://siteurl.com/
has og:type of ‘article’. The property ‘object’ requires an object of og:type ‘shares:object’.

so what is the problem?

http://wordpress.org/extend/plugins/wordpress-seo/