php - Facebook events graph not working -

i'm trying facebook page events. i've checked app id , app secret correct , still keep getting error.

<?php ini_set('display_startup_errors',1); ini_set('display_errors',1); error_reporting(-1);  ob_start();  require 'facebook/src/facebook.php';  $fb = new facebook(array(        'appid'=>'appid',        'secret'=>'appsecret'       ) ); $page_events = $fb->api('/pageid/events?fields=description,location,name,owner,cover,start_time,end_time', 'get'); printf ('<pre>%s</pre>', $page_events);  ?> 

the error message:

uncaught oauthexception: invalid oauth access token signature. thrown in

i'm not sure you've implemented or not code missing-

1. user login/authentication

   the code not authenticating user. after creating $fb object; use this-

   $user_id = $fb->getuser(); if($user_id) {    try {        // proceed api calls - user authenticated @ point     } catch(facebookapiexception $e) {       $login_url = $fb->getloginurl(array( 'scope' => 'manage_pages'));       header ("location: $login_url");       error_log($e->gettype());       error_log($e->getmessage());    }    } else {    $login_url = $fb->getloginurl(array( 'scope' => 'manage_pages'));    header ("location: $login_url"); } 

2. permissions

   the documentation says-

   for page events-

   • any access token can used view publicly shared events.
   • a user access token required retrieve events visible person.
   • a page access token required retrieve other events.

   i think trying fetch events in page, you'll needing page access token.

   to page access token: $fb->api("/page_id?fields=access_token");. use token return original call page's events-

   $page_events = $fb->api('/pageid/events?access_token='.$page_access_token.'&fields=description,location,name,owner,cover,start_time,end_time', 'get'); 

(if required, can never expiring page token page: see here)