Problem when closing Lightbox when I call AJAX

Question

I’m in trouble when on this site http://santins.com.br/_z/holcim session access PROJETO and click on RELEASES. While I do not click on any titles that loads via AJAX the content of the post, the LIGHTBOX closes, but by clicking on the title and ajax loading the content I can no longer close it. What could be this problem?

My AJAX:

// Classe para posts AJAX
jQuery.noConflict();
    jQuery(document).ready(function($){
        $.ajaxSetup({cache:false});
        $("a.ajax").click(function(){
            var post_url = $(this).attr("href");
            var post_id = $(this).attr("rel");
            $("#tabs").html('<div class="loading">loading...</div>');
        $("#tabs").load(post_url);
        return false;
        });
    });