Pager not showing on subscribers list

I have a website for a customer where I created a user (let's say admin2) for the customer to administer his wbsite (it's a different user the site-wide administration user which I control).
When I as administrator log in and go to admin/people/newsletter page everything is ok.
But when admin2 logs in and navigates to admin/people/newsletter page the list that shows the subscribed users doesn't show the pager at the end.

I changed the code in includes/simplenews.admin.inc file , in simplenews_subscription_list_form() function (line : 1169) from

<?php
$form['pager'] = array('#theme' => 'pager');
?>

to

<?php
  $form['custom_pager'] = array(
  '#markup' => theme('pager',array())
  );
?>

and now the pager is showing up on admin's2 admin/people/newsletter page.
It seems like the pager function does not output based on either the role or the theme ( I use garland as administration theme for site administrator and omega subtheme for admin2 interface ).

Let me know if somebody checks about it , so that I can close this issue..