Form tags removed when dialog is created

Form tags removed when dialog is created

I have a form inside a dialog:
<div id="init_dialog" title="Information Required">
  <form action="" method="post" id="init_form" onsubmit="return false;">
    <input type="hidden" name="emp_pk" id="emp_pk" value="1234" />
    <fieldset><legend>Information</legend>
      <label for="init_info">Please Enter some information</label>
      <input type="text" id="init_info" name="init_info" value="information" />
    </fieldset>
  </form>
</div>
In jquery:
jQuery(document).ready(function() {
  jQuery('#init_dialog').dialog({
    bgiframe:true,
    autoOpen:false,
    modal:true,
    width:700,
    buttons: {
      Cancel:function(){ jQuery(this).dialog('close'); },
      "Get Info":function(){ alert(jQuery('#init_form').serialize()); }
    }
  });
}
When I open the dialog and click the "Get Info" button (triggers the alert), I expect to see a string like this:
emp_pk=1234&init_info=information
Instead, I get a blank alert box.
I did a check with firebug and noticed that when the dialog is created, the <form> tags are completely stripped out.  The demo on jqueryUI.com does NOT strip out the form tag.  Am I missing something?  This happens in both IE7 and Firefox 3.5
I'm using JqueryUI 1.7.2