Uncaught OAuthException

伙计们请帮我解决这个问题。。。我的程序给出的错误是"致命错误：未捕获OAuthException：验证应用程序时出错"。。。我的程序代码是：

require ("src/facebook.php");
$appapikey = 'xxx';
$appsecret = 'xxx';
$facebook = new Facebook($appapikey, $appsecret);
$user_id = $facebook->getUser();
$friends = $facebook->api('friends.get');

echo "<p>Hello <fb:name uid='"$user_id'" useyou='"false'" linked='"false'" firstnameonly='"true'"></fb:name>, you have ".count($friends)." friends";
foreach($friends as $friend){
     $infos.=$friend.",";
}
$infos = substr($infos,0,strlen($infos)-1);
$gender=$facebook->api_client->users_getInfo($infos,'sex');
$gender_array = array(); 
foreach($gender as $gendervalue){
     $gender_array[$gendervalue[sex]]++;
}
$male = round($gender_array[male]*100/($gender_array[male]+$gender_array[female]),2);
$female = 100-$male;
echo "<ul><li>Males: $male%</li><li>Females: $female%</li></ul>";