Problème Facebook api connect

Bonjour, j'ai un Error 500.

Voici donc mon code :

require 'API/facebook.php';
$facebook = new Facebook(array(
    'appId' => '181111771982863',
    'secret' => 'caché',
    'cookie' => true
    ));
$user = $facebook->getUser();
if(empty($user)) {
   header('Location:'.$facebook->getLoginUrl(array(
        'locale' => 'fr_FR'
)));

} else {
    try {
        $uid = $facebook->getUser();
        $me = $facebook->api('/me');
} catch (FacebookApiException $e) { print_r($e); }
}
if(isset($me)) {
    $fql = "select uid,name,pic_big, from user where uid=$uid";
    $param = array(
        'method' => 'fql.query',
        'query' => $fql,
        'callback' => ''
);
    $fb = $facebook->api($param);
    print_r($fb);
}

Merci d'avance.