Drupal 7 Display a block on custom tab
Should be next:

function custom_morebuttons_menu() {
  $items['node/%node/calendario-corsi'] = array(
    'title' =&gt; 'Calendario corsi',
    'page callback' =&gt; 'custom_node_calendario_corsi_page',
    'page arguments' =&gt; array(1),
    'access callback' =&gt; 'user_is_logged_in',
    'type' =&gt; MENU_LOCAL_TASK,
    'weight' =&gt; 10,
  );

  return $items;
}

function custom_node_calendario_corsi_page($node) {
  $node = node_load($arg);
  if (($node-&gt;type == 'centro') || ($node-&gt;type == 'sede')) {
    // I assume you will add some behaviour code for this, next make no sense.
    return $node; 
  }
  return false;
}