Drupal 7 Display a block on custom tab

Question

I would like to display a view block on a custom tab I created as follows, but the tab is always empty. The block has the option to be shown only on specified path node/%node/calendario-corsi. Is it correct to have an empty page callback?

function custom_morebuttons_menu() {

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

  return $items;
}


function custom_node_calendario_corsi_load($arg) {

  $node = node_load($arg);

  if($node->type == 'centro' || $node->type == 'sede') {

    return $node; }

  return FALSE;
}


function custom_node_calendario_corsi_page($arg) {

  return '';
}

Answer 1

Should be next:

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

  return $items;
}

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

Answer 2

This is my working solution:

function custom_morebuttons_menu() {

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

  return $items;
}


function custom_node_calendario_corsi_load($arg) {

  $node = node_load($arg);

  if ($node->type == 'centro' || $node->type == 'sede') { return $node; }

  return false;
}


function custom_node_calendario_corsi_page($node) {

  if ($node->type == 'centro') { return views_embed_view('centro_autenticato_calendario_corsi', 'block_1', $node->nid);

  } else if ($node->type == 'sede') { return views_embed_view('sede_autenticato_calendario_corsi', 'block_1', $node->nid); }
}