integrating Wordpress with Symfony

I have a site built with Symfony 1.2. I'm trying to integrate Wordpress 2.8.4 into it to power my blog. I followed the instructions at http://www.theodo.fr/blog/2009/03/integrate-wordpress-into-symfony/, including the 2 steps in the comments at http://www.theodo.fr/blog/2009/03/integrate-wordpress-into-symfony/comment-page-1/#comment-573. My actions.class.php file looks like this:

 <?php
 class sfWordpressActions extends sfActions
 {
   public function executeIndex(sfWebRequest $request)
   {

     // Don't load symfony's I18N
     $standard_helpers = sfConfig::get('sf_standard_helpers');
     $standard_helpers = array_diff($standard_helpers, array('I18N'));
     sfConfig::set('sf_standard_helpers', $standard_helpers);

     define('WP_USE_THEMES', true);
     chdir( dirname(__FILE__) . DIRECTORY_SEPARATOR . '..' . DIRECTORY_SEPARATOR . '..' . DIRECTORY_SEPARATOR . '..' . DIRECTORY_SEPARATOR . 'lib' . DIRECTORY_SEPARATOR . 'vendor' . DIRECTORY_SEPARATOR . 'wordpress' );
     global $wpdb;

     ob_start();
     require_once( 'wp-blog-header.php' );
     $this->blog = ob_get_contents();
     if (function_exists('is_feed') && is_feed())
     {
       ob_end_flush();
       throw new sfStopException();
     }
     else
     {
       ob_end_clean();
     }
   }
 }
    ?>

My indexSuccess.php is simply

This is a test
<?php echo $blog ?>

And my wp-blog-header.php is

<?php
/**
 * Loads the WordPress environment and template.
 *
 * @package WordPress
 */

if ( !isset($wp_did_header) ) {
  $wp_did_header = true;

  require_once( dirname(__FILE__) . '/wp-load.php' );

  // @HACK FABRICE
  // All variables defined here are considered global by Wordpress
  $local_global_vars = get_defined_vars();
  foreach($local_global_vars as $local_name => $local_value)
  {
    $GLOBALS[$local_name] = $local_value;
  }
  // Don't create new global variables ourselves, and do not overwrite other global variables, for example $name...
  unset($local_name, $local_value, $local_global_vars);
  // @HACK FABRICE

  wp();

  // @HACK Fabrice
  global $posts;
  // @HACK Fabrice

  require_once( ABSPATH . WPINC . '/template-loader.php' );
}

Here's my problem:

As it is, I get nothing when I go to the page. None of my Symfony headers, no Wordpress content, nothing. When I comment out the line "require_once( 'wp-blog-header.php' );" in actions.class.php, everything works fine but there is no Wordpress content. This leads me to believe that that Symfony is dying somewhere in the process of including the Wordpress stuff. How this might be fixed?