title: facebook xid doesn't work
body: <p>i need separate comment thread for each post on my website, so i followed instructions at <a href="http://developers.facebook.com/blog/post/472" rel="nofollow">http://developers.facebook.com/blog/post/472</a>, ie i inserted the code:</p>
  
  <pre><code> &lt;div id="fb-root"&gt;&lt;/div&gt;
   &lt;script src="http://connect.facebook.net/en_US/all.js#xfbml=1"&gt;&lt;/script&gt;
   &lt;fb:comments href="www.mysite.com" xid="postPOST_ID_HERE"&gt;&lt;/fb:comments&gt;
  </code></pre>
  
  <p>under each post.</p>
  
  <p>but it doesn't work and there is SAME comments thread under each post.</p>
  
  <p>if i try this code:</p>
  
  <pre><code> &lt;div id="fb-root"&gt;&lt;/div&gt;
   &lt;script src="http://connect.facebook.net/en_US/all.js#xfbml=1"&gt;&lt;/script&gt;
   &lt;fb:comments href="http://www.mysite.com/news.php?id=POST_ID_HERE"&gt;&lt;/fb:comments&gt;
  </code></pre>
  
  <p>it seems to work, ie i get separate comment thread per post. but according to facebook instructions href parameter needs to be canonical url. am i doing something wrong in the first case or is the second example way to go (even if against facebook manual)?</p>