使用Twitter API签署用户 - 如何转向oauth_token＆amp; oauth_verifier进入Access Token

Question

这是我正在使用的教程：

http://net.tutsplus.com/tutorials/php/how-to-authenticate-users-with-twitter-oauth/

在获取访问令牌的最后一步之前，一切似乎都很好，我得到的错误是：

Notice: Undefined index: oauth_token in /var/www/vhosts/opticalexpress.com/httpdocs/facebook/2011/ambassador-referral/classes/twitteroauth.php on line 118

Notice: Undefined index: oauth_token_secret in /var/www/vhosts/opticalexpress.com/httpdocs/facebook/2011/ambassador-referral/classes/twitteroauth.php on line 118

据我所知，一切都应该有效：/

这是代码：

require_once('classes/twitteroauth.php');
session_start();

// The TwitterOAuth instance
$twitteroauth = new TwitterOAuth('xxxx', 'xxxx');
// Requesting authentication tokens, the parameter is the URL we will be redirected to
$request_token = $twitteroauth->getRequestToken('http://www.domain.com/tweet.php');

// Saving them into the session
$_SESSION['oauth_token']        = $request_token['oauth_token'];
$_SESSION['oauth_token_secret'] = $request_token['oauth_token_secret'];

// If everything goes well..
if($twitteroauth->http_code==200){
    // Let's generate the URL and redirect
    $url = $twitteroauth->getAuthorizeURL($request_token['oauth_token']);
    echo '<a href="'.$url.'">authorise</a>';
} else {
    // It's a bad idea to kill the script, but we've got to know when there's an error.
    die('Something wrong happened.');
}

if(!empty($_GET['oauth_verifier']) && !empty($_SESSION['oauth_token'])){
    // We've got everything we need

    // TwitterOAuth instance, with two new parameters 
    $twitteroauth = new TwitterOAuth('xxxx', 'xxxx', $_SESSION['oauth_token'], $_SESSION['oauth_token_secret']);
    // Let's request the access token
    $access_token = $twitteroauth->getAccessToken($_GET['oauth_verifier']);
    // Save it in a session var
    $_SESSION['access_token'] = $access_token;
    // Let's get the user's info
    //$user_info = $twitteroauth->get('account/verify_credentials');
    // Print user's info
    //print_r($user_info);
} else {
    // Something's missing, go back to square 1
    echo 'something missing';
}

我真的疯了，试图让这个工作，任何想法？