I am trying to enable a disabled tab in Jquery but it doesn't work I have my tabs:

<!--Jquery AJAX Tabs Start-->
<div id="signuptabs">
     <ul>
         <li><a href="type.php"><span>Number type</span></a></li>
         <li><a href="ber.php"><span>Choose Number</span></a></li>
         <li><a href="ces.php"><span>Devices</span></a></li>
         <li><a href="ups.php"><span>Ring Groups</span></a></li>
    <li><a href="t.php"><span>IVR Text</span></a></li>
        <li><a href="nu.php"><span>IVR Menu</span></a></li>
        <li><a href="nfo.php"><span>Billing Information</span></a></li>
     </ul>

</div>
<!--Jquery AJAX Tabs End-->

Then I have my Javascript:

  $(document).ready(function() {
    $("#signuptabs").tabs({ disabled: [1, 2, 3, 4, 5, 6, 7] });

//number type button
$('#target').click(function() {
$('#signuptabs').enableTab(2); // enables third tab
 });

 }); 

I have a button with an ID 'target' that when clicked is supposed to enable the (2) tab. The tabs show as disabled but will not enable. what is wrong??