使用Codenvy到OAuth谷歌与PHP

I am fairly new to codenvy and php but I have doublechecked the following, yet I am still not asked to oauth into google when I launch this with the following code. I followed instructions from here. any obvious mistakes in the below?

https://developers.google.com/analytics/solutions/articles/hello-analytics-api

 <?php
  require_once 'src/Google/Client.php';
  require_once 'src/Google/Service/Analytics.php';
   session_start();

   $client = new Google_Client();
   $client->setApplicationName('Hello Analytics API Sample');

    // Visit https://console.developers.google.com/ to generate your
    // client id, client secret, and to register your redirect uri.
    $client->setClientId('CONFIRMED THIS IS CORRECT');
    $client->setClientSecret('CONFIRMED THIS IS CORRECT');
    $client->setRedirectUri('https://codenvycorp.com/api/oauth/callback');
    $client->setDeveloperKey('CONFIRMED THIS IS CORRECT');
    $client->setScopes(array('https://www.googleapis.com/auth/analytics.readonly'));

    // Magic. Returns objects from the Analytics Service instead of associative arrays.
    $client->setUseObjects(true);

   if (isset($_GET['code'])) {
    $client->authenticate();
    $_SESSION['token'] = $client->getAccessToken();
    $redirect = 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
    header('Location: ' . filter_var($redirect, FILTER_SANITIZE_URL));
   }

   if (isset($_SESSION['token'])) {
    $client->setAccessToken($_SESSION['token']);
   }

   if (!$client->getAccessToken()) {
      $authUrl = $client->createAuthUrl();
      print "<a class='login' href='$authUrl'>Connect Me!</a>";

    } else {
      $analytics = new apiAnalyticsService($client);
      runMainDemo($analytics);
    }  

   echo 'Hello World 321';
   ?>

If your project is public, please, share it with Codenvy's factory feature. So everyone will be able to look what is wrong with OAuth integration. (You can access factory on left panel of the IDE)