php - Internationalisation language switch?

I am using the internationalisation block for basic page translation between Spanish and English. By default the content is in Spanish. When I change the language to English the page content is translated, however the autonav appears blank. I have used page CID's to determine the language differences. In my header.php file for my theme I am using the follow statement:

if(!$c->getAttribute('english_menus')) {
$lh = Loader::helper('section', 'multilingual');
$lang = $lh->getLanguage();
$bt = BlockType::getByHandle('autonav');
$bt->controller->displayPages = 'custom';
if ($lang == "en_EN"){
  $bt->controller->displayPagesCID = 166; //English section cID
} else {
  $bt->controller->displayPagesCID = 171; //Spanish section cID
}
$bt->controller->orderBy = 'display_asc';
$bt->render('templates/top_nav/view');
}
Copy code

This displays the top level navigation fine. however when the country flag is selected the auto nav menu disappears and does not display in english

Many Thanks