Open Graph Warnings & Critical Errors

I use the last version (1.4.19) of plugin on a wp multisite and i have this problems with Open Graph, why is this happening when I insert the URL into the debugger / linterand and how can i fix this?

1.Critical Errors That Must Be Fixed
Bad Response Code
URL returned a bad HTTP response code.

2.Open Graph Warnings That Should Be Fixed
Parser Mismatched Metadata
The parser’s result for this metadata did not match the input metadata. Likely, this was caused by the data being ordered in an unexpected way, multiple values being given for a property only expecting a single value, or property values for a given property being mismatched. Here are the input properties that were not seen in the parsed result: ‘article:section’

This is an example of what the plugin creates in each post.

<!– This site is optimized with the Yoast WordPress SEO plugin v1.4.19 – http://yoast.com/wordpress/seo/ –>
<title>Post Title</title>
<meta name=”description” content=”Post description.”/>
<meta name=”keywords” content=”Post, keywords”/>
<link rel=”canonical” href=”http://mysite.com/post-title&#8221; />
<link rel=”author” href=”https://plus.google.com/u/0/114744978668502360302″/&gt;
<link rel=”publisher” href=”https://plus.google.com/101798453297827886314″/&gt;
<meta property=”og:locale” content=”en_EN” />
<meta property=”og:type” content=”article” />
<meta property=”og:title” content=”Post title” />
<meta property=”og:description” content=”Post description.” />
<meta property=”og:url” content=”http://mysite.com/post-title&#8221; />
<meta property=”og:site_name” content=”MySite.Com” />
<meta property=”article:publisher” content=”https://facebook.com/mysitecom&#8221; />
<meta property=”article:tag” content=”keywords 1″ />
<meta property=”article:tag” content=”keywords 2″ />
<meta property=”article:tag” content=”keywords 3″ />
<meta property=”article:tag” content=”keywords 3″ />
<meta property=”article:tag” content=”keywords 4″ />
<meta property=”article:section” content=”keywords 5″ />
<meta property=”article:section” content=”keywords 6″ />
<meta property=”article:published_time” content=”2013-11-05T00:03:14+00:00″ />
<meta property=”article:modified_time” content=”2013-11-05T00:05:41+00:00″ />
<meta property=”fb:app_id” content=”10706666011574″ />
<meta property=”og:image” content=”http://mysite.com/wp-content/uploads/sites/3/2013/11/post-title-image.jpg&#8221; />
<meta name=”twitter:card” content=”summary”/>
<meta name=”twitter:site” content=”@mysitecom”/>
<meta name=”twitter:domain” content=”MySite.Com”/>
<meta name=”twitter:creator” content=”@Author1″/>
<!– / Yoast WordPress SEO plugin. –>

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