Merge branch 'ticket/11355' into develop-olympus

* ticket/11355:
  [ticket/11355] Referred proper variable when validating selection.
  [ticket/11355] Wrong error message when no user is selected.

phpBB/includes/acp/acp_groups.php

@@ -179,6 +179,10 @@ class acp_groups
 			break;
 
 			case 'deleteusers':
+				if (empty($mark_ary))
+				{
+					trigger_error($user->lang['NO_USERS'] . adm_back_link($this->u_action . '&action=list&g=' . $group_id), E_USER_WARNING);
+				}
 			case 'delete':
 				if (!$group_id)
 				{
@@ -795,4 +799,4 @@ class acp_groups
 	}
 }
 
-?>
+?>