Почему не работает сортировка новостей по ajax, где я допускаю ошибку?

$cat_info = get_vars("category");
if (!is_array($cat_info)) {
	$cat_info = [];
	$db->query("SELECT * FROM " . PREFIX . "_category ORDER BY posi ASC");
	while ($row = $db->get_row()) {
		$cat_info[$row['id']] = [];
		foreach ($row as $key => $value) {
			$cat_info[$row['id']][$key] = stripslashes($value);
		}
	}
	set_vars("category", $cat_info);
	$db->free();
}

if (trim($ajax_sort['category']) != '') {
	if ($config['allow_multi_category']) {
		$ajax_where[] = "category NOT REGEXP '[[:<:]](" . str_replace(',', '|', $ajax_sort['category']) . ")[[:>:]]'";
	} else {
		$ajax_where[] = "category NOT IN('" . str_replace(',', "','", $ajax_sort['category']) . "')";
	}
}