This is my hook_menu:

$items['events/%event'] = array(
  'title' => 'Event',
  'title callback' => 'entity_label',
  'title arguments' => array('event', 1),
  'page callback' => 'events_view',
  'page arguments' => array(1),
  'access callback' => 'entity_access',
  'access arguments' => array('view', 'event', 1),
  'file' => 'events.pages.inc',
);

return $items;

But when I navigate to events/2 there's a 404 error waiting! Here's the page:

As you can see, my Event has been successfully created (it exists in database and its id is definitely 2) but the requested page could not be found and Shortcuts menu and Navigation block has disappeared.
What possibly could I mistaken?
Feel free to ask for more information.
Thanks.