At my first site, where I have Yoast's Wordpres SEO plugin v. 0.1.4 is everything alright, but at other sites where I have version 0.1.8 or 0.2, Google doesn't pick up my meta description.
I noticed that at newer versions there are single quotes used. At earlier versions there are double quotes used.
newer versions: <meta name='description' content='some text'/>
older versions: <meta name="description" content="some text"/>
I think there should be double quotes used for meta description...