API を使用して Facebook ページのユーザー アフィニティを正確に判断するにはどうすればよいですか?

FB.api({
    method:     "pages.isFan",
    page_id:        my_page_id,
},  function(response) {
        console.log(response);
        if(response){
            alert('You Likey');
        } else {
            alert('You not Likey :(');
        }
    }
);

function parsePageSignedRequest() {
    if (isset($_REQUEST['signed_request'])) {
      $encoded_sig = null;
      $payload = null;
      list($encoded_sig, $payload) = explode('.', $_REQUEST['signed_request'], 2);
      $sig = base64_decode(strtr($encoded_sig, '-_', '+/'));
      $data = json_decode(base64_decode(strtr($payload, '-_', '+/'), true));
      return $data;
    }
    return false;
  }
  if($signed_request = parsePageSignedRequest()) {
    if($signed_request->page->liked) {
      echo "This content is for Fans only!";
    } else {
      echo "Please click on the Like button to view this tab!";
    }
  }