Adding certification user list link

main/gradebook/lib/fe/displaygradebook.php

@@ -538,7 +538,7 @@ class DisplayGradebook
                 	$my_file= substr($_SESSION['gradebook_dest'],0,5);
                 		
 					//$header .= '<td style="vertical-align: top;"><a href="gradebook_flatview.php?'.$my_api_cidreq.'&selectcat=' . $catobj->get_id() . '">'.Display::return_icon('stats.png', get_lang('FlatView'),'','32').'</a>';					
-					//$header .= '<td style="vertical-align: top;"><a href="gradebook_display_certificate.php?'.$my_api_cidreq.'&amp;cat_id='.(int)$_GET['selectcat'].'">'.Display::return_icon('certificate_list.png', get_lang('GradebookSeeListOfStudentsCertificates'),'','32').'</a>';
+					$header .= '<td style="vertical-align: top;"><a href="gradebook_display_certificate.php?'.$my_api_cidreq.'&amp;cat_id='.(int)$_GET['selectcat'].'">'.Display::return_icon('certificate_list.png', get_lang('GradebookSeeListOfStudentsCertificates'),'','32').'</a>';
 					
 					$visibility_icon    = ($catobj->is_visible() == 0) ? 'invisible' : 'visible';
 			        $visibility_command = ($catobj->is_visible() == 0) ? 'set_visible' : 'set_invisible';