Dialog does not display when reopened

If I open a dialog box, close it, and then try to re-open it again, the dialog is displayed the first time but not the second time. When the dialog opens the second time, the titlebar is visible but the main dialog contents are not.

My code is as follows:

(dialog html)

          <div class='dialog_wrapper' style='display: none;'>
            <div class='dialog'>
                w00t
            </div>
          </div>

(dialog display code)

          <script type='text/javascript'>
            //<![CDATA[
              function open_dialog() {
                jQuery(".dialog_wrapper").dialog({
                    draggable: false,
                    height: 265,
                    width: 350,
                    modal: true,
                    overlay: { 
                        opacity: 0.5, 
                        background: "#000000" 
                    },
                    resizable: false
                }).show();
              }
            //]]>
          </script>

(the link)

          <a href='#' onClick='open_dialog();'>Open dialog</a>

I took a cursory glance, and it appears that the wrapper divs are not being removed when the dialog is closed. Perhaps that is the problem?