[development] problem with theme form drupal_render

hi: i have a problem. I have a theme for my form, but I can't show the message error. What can I do ? thanks. *form.tpl.php* <?php if ($show_messages && $messages): print $messages; endif; ?> <?php echo drupal_render($form["nombres"]); ?> <?php echo drupal_render($form["submit"]); ?>