title: How to get ads to refresh using googletag.pubads().refresh()?
body: <p>I have an ad and a link in a page like so:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;head profile="http://www.w3.org/1999/xhtml/vocab"&gt;
  &lt;title&gt;DPT - Asynchronous + Single Rest Architecture&lt;/title&gt;
    &lt;script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.0/jquery.min.js"&gt;&lt;/script&gt;
    &lt;script type='text/javascript'&gt;
      var googletag = googletag || {};
      googletag.cmd = googletag.cmd || [];
      (function() {
      var gads = document.createElement('script');
      gads.async = true;
      gads.type = 'text/javascript';
      var useSSL = 'https:' == document.location.protocol;
      gads.src = (useSSL ? 'https:' : 'http:') +
      '//www.googletagservices.com/tag/js/gpt.js';
      var node = document.getElementsByTagName('script')[0];
      node.parentNode.insertBefore(gads, node);
      })();
    &lt;/script&gt;
    &lt;script type='text/javascript'&gt;
      googletag.cmd.push(function() {
      googletag.pubads().enableAsyncRendering();
      googletag.defineSlot('/1001256/Home_Top_Leaderboard_728x90', [728, 90], 'div-gpt-ad-1342320102476-72').addService(googletag.pubads());
      googletag.pubads().enableSingleRequest();
      googletag.enableServices();
      });
  &lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;div id="div-gpt-ad-1342320102476-72" style="width:728px; height:90px;"&gt;
        &lt;script type="text/javascript"&gt;
          googletag.cmd.push(function() { googletag.display('div-gpt-ad-1342320102476-72'); });
        &lt;/script&gt;
      &lt;/div&gt;
      &lt;a id="refresh" href="#"&gt;Refresh ad&lt;/a&gt;
      &lt;script type='text/javascript'&gt;
      (function ($) {
          $('#refresh').click(function() {
           googletag.cmd.push(googletag.pubads().refresh());
          return false;
          });
      })(jQuery);
      &lt;/script&gt;
  &lt;/body&gt;
  &lt;/html&gt; 
  </code></pre>
  
  <p>The first time I click the link, the ad refreshes. All other times nothing happens. Even just calling the refresh() method in Firebug etc does nothing after the first time. </p>
  
  <p>What's wrong with the above? </p>