title: jQuery data() returns undefined constantly
body: <p>Below is the HTML and following jQuery. If I return the attr("data-conn"); it alerts the correct value but using .data("conn") it doesn't. Why?</p>
  
  <pre><code>&lt;span&gt;
      &lt;!-- ... --&gt;
      &lt;a href="link.html" class="textbutton"  data-conn="text3"&gt;
          &lt;img src="/images/image.png"&gt;
      &lt;/a&gt;
  &lt;/span&gt;
  &lt;span style="width:610px;height:200px;float:right; background-color:#bcbcbc;font-size:15px;line-height:15px;"&gt;
      &lt;div class="texts" id="text1"&gt;Initial Header&lt;/div&gt;
      &lt;span class="texts" id="text2" style="display:none;"&gt;Text for another one&lt;/span&gt;
      &lt;span class="texts" id="text3" style="display:none;"&gt;Content Text&lt;/span&gt;
  &lt;/span&gt;
  
  &lt;script type="text/javascript"&gt;
      $(".textbutton").click(function(){
          var link = $(this).data("conn");
          alert(link);
          $(".texts").fadeOut(1000, function() {
              $("#text2").fadeIn(1000);
          });
          return false;
      });
  &lt;/script&gt;
  </code></pre>