Sử dụng hook_menu() với hook_permission()

Can someone see anything wrong with this hook_menu() and hook_permission() code? I am able to see the permissions in the admin menu, admin/people/permissions. I allow access tolos user front for authenticated users and save the settings. Then, I clear all caches and try to access los/register. I am getting You are not authorized to access this page. when I try with either administrative or authenticated users. I have cleared the cache, logged in and out and even closed the browser and restarted it refreshing ever step of the way.

/**
 * Implements hook_permission
 */
function los_permission() {
  return array(
    'los user front' => array(
      'title' => t('LOS User Frontend'),
      'description' => t('Access to LOS user frontend.'),
    ),
    'los user back' => array(
      'title' => t('LOS User Backend'),
      'description' => t('Access to LOS user backend'),
    ),
    'los admin back' => array(
      'title' => t('LOS Administration Backend'),
      'description' => t('Access to LOS administration backend.'),
    ),
  );
}

/**
 * Implements hook_menu
 */
function los_menu() {
  $items = array();

  $items['los/register'] = array(
    'title' => 'LOS Register',
    'description' => 'Large order system registration page',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('los_register'),
    'access arguments' => array('los user front'),
  );

  //... more $items here ...

  return $items;
}