[Plugin: NextGEN Gallery] No album on page

If I display a page in this mode with an album

<?php
$my_id = 28;
$post_id_28 = get_post($my_id);
$content = $post_id_28->post_content;
echo $content;
?>

it show only [album id=1 template=extend] without any photo…any solution?

kikko088