Looks like your missing this script in your tpl,
OK so at the bottom of that page you should have the options which i can see by your page you have, then after that the below script needs to be added
<script defer="defer">
$(document).ready(function()
{
$("#th")
.tablesorter({widthFixed: true, widgets: ['zebra']})
.tablesorterPager({container: $("#pager")});
}
);
</script>
If your using the code above then that table needs to have the class, <table id="th" class="tablesorter">