jQuery UI Tabs – Ajax – PHP … 404

i don’t know if it’s already asked but i cannot find with search here and on search engine..

the html

<div id="tabs">
  <ul>
    <li><a href="call.php?catid=0">Tab1</a></li>
    <li><a href="call.php?catid=3">Tab2</a></li>
    <li><a href="call.php?catid=8">Tab3</a></li>
    <li><a href="call.php?catid=6">Tab4</a></li>
  </ul>
</div>

the javascript

jQuery("#tabs").tabs({
  ajaxOptions: {
    error: function(xhr, status, index, anchor) {
      jQuery(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible.");}}});

call.php

define('WP_USE_THEMES', false);
require '../../../wp-blog-header.php';
$cat = (int) $_GET['catid'];
$args = array ('numberposts' => '5', 'post_type' => 'post', 'suppress_filters' => 0, 'category' => $cat);
$recent_posts = wp_get_recent_posts($args);
foreach ($recent_posts as $recent):
if (has_post_thumbnail($recent['ID']))
$fpimg = get_the_post_thumbnail($recent['ID'], 'fpslide', array ('title' => esc_attr($recent['post_title'])));
else
$fpimg = '<img src="'.get_template_directory_uri().'/image/logo-slide.jpg" alt="" title="'.esc_attr($recent['post_title']).'" />';
?>
                    <a href="<?php echo get_permalink($recent['ID']);?>"><?php echo $fpimg;?></a>
<?php endforeach;?>

the problem is i can’t get the content, always show the error msg (“Couldn’t load this tab….”).
on firebug the status say 404, but on Response & HTML tab i can see the right content.. so what did i do wrong?