aplicacion facebook php

[davidbons]

Código:

<?php

	require 'facebook.php';
	//facebook application
    //set facebook application id, secret key and api key here
    $fb['appid' ] = "152687434769564";
    $fb['api'   ] = "f7655cb8e9497827b08ea0e068ff8a91";
    $fb['secret'] = "************************";

    $fb['baseUrl']    =   "http://www.tecnovacartama.com/facebook3/"; 
    $fb['appBaseUrl'] =   "http://apps.facebook.com/tecnovainforma/"; 
    $fb['cvUrl'] ="http://www.tecnovacartama.com/facebook3/";
	$fb['cvPage'] = "http://apps.facebook.com/tecnovainforma/";  
	
	
    $facebook = new Facebook(array(
      'appId'  => $fb['appid'],
      'secret' => $fb['appsecret'],
      'cookie' => true,
    ));

	

 $session = $facebook->getSession();
    $loginUrl = $facebook->getLoginUrl(
            array(
            'canvas'    => 1,
            'fbconnect' => 0,
            'req_perms' => 'email,publish_stream,read_stream,user_photos'
            )
    );
    $me = null;

   
	
    if(!empty($session)){
	    echo "<script type='text/javascript'>top.location.href='".$loginUrl."';</script>";
        exit;
    }else{
		
        try{
           $uid = $facebook->getUser();
			
            $me = $facebook->api('/me');
			
        }catch(FacebookApiException $e){
		  echo $e;
	}	  
		  
    }
?>

Siempre se produce la excepción
OAuthException: Invalid OAuth access token signature
Se que en la pagina http://developers.facebook.com/docs/authentication/ hay documentación sobre el tema pero
pero no se como arreglarlo exactamente ¿alguna idea?