get_pages "numbers" and sort_order "desc" doesn't work

Is there something wrong with this code? Because i can’t get to display the latest grandchild of ‘2’.
Also, sort_order = desc doesn’t display anything.

Thanks very muhc

<?php
echo 'get pages';
$parent = '2';
$args=array(
  'child_of' => $parent,

  'post_type' => 'page',
  'sort_column'=> 'post_date',
  'sort_order' => 'desc',
'number' => 7

);
$pages = get_pages($args);
if ($pages) {
  foreach($pages as $post) {
    setup_postdata($post);
    if ($post->post_parent != $parent ) { ?>
      <p><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></p>
      <?php
    }
  } // foreach($pages
} // if ($pages
?>