Facebook通过PHP cURL登录 - cookies

Question

我有这段代码：

$login_email = '***';
$login_pass = '****';
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://www.facebook.com/login.php');
curl_setopt($ch, CURLOPT_POSTFIELDS,'email='.urlencode($login_email).'&pass='.urlencode($login_pass).'&login=Login');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_COOKIEJAR, "cookies.txt");
curl_setopt($ch, CURLOPT_COOKIEFILE, "cookies.txt");
curl_setopt($s, CURLOPT_COOKIESESSION, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.3) Gecko/20070309 Firefox/2.0.0.3");
curl_setopt($ch, CURLOPT_REFERER, "http://www.facebook.com");
$page = curl_exec($ch) or die(curl_error($ch));
echo $page;

Facebook说，我应该在浏览器中打开cookie。文件cookies.txt为空。