使用Graph API和PHP发布托管照片

我正在尝试制作一个PHP脚本，该脚本将在不使用PHP SDK的情况下将托管照片发布到用户的配置文件中。这就是我现在拥有的：

<?php
   $app_id = "[My App ID]";
   $app_secret = "[My App Secret]";
   $post_login_url = "[current page]";
   $code = $_REQUEST["code"];
   //Obtain the access_token with publish_stream permission 
   if(empty($code)){ 
      $dialog_url= "http://www.facebook.com/dialog/oauth?"
       . "client_id=" .  $app_id 
       . "&redirect_uri=" . urlencode( $post_login_url)
       .  "&scope=publish_stream";
      echo("<script>top.location.href='" . $dialog_url 
      . "'</script>");
     }
    else {
      $token_url="https://graph.facebook.com/oauth/access_token?"
       . "client_id=" . $app_id 
       . "&redirect_uri=" . urlencode( $post_login_url)
       . "&client_secret=" . $app_secret
           . "&code=" . $code;
          $response = file_get_contents($token_url);
          $params = null;
          parse_str($response, $params);
          $access_token = $params['access_token'];



         // This would probably be where my problem is
         $graph_url= "https://graph.facebook.com/me/photos?"
         . "access_token=" .$access_token;
$postdata = http_build_query(
         array(
          'source' => $imageurl, //this variable has been properly defined
          'message' => $image_description //this, too, has been defined
            )
          );
         $opts = array('http' =>
         array(
          'method'=> 'POST',
          'header'=>
            'Content-type: application/x-www-form-urlencoded',
          'content' => $postdata
          )
         );
      }
?>

运行此程序时，会创建一个带有应用程序名称的新相册，但不会上载该文件。有什么办法让它发挥作用吗？如果有人知道PHP甚至javascript的解决方案，请分享

-Cory