title: rel=image_src isn't changing the thumbnail
body: <p>I added this code to the head but when I try to post something about a website inside a Facebook page, the image that I specified is still not showing up as an option.  I'm using wordpress as a CMS. Any ideas why?  </p>
  
  <pre><code>&lt;meta content="something" name="title"&gt;
  &lt;meta content="something="og:description"&gt;    
  &lt;link href="thumbnail.jpeg" rel="image_src"&gt;
  </code></pre>