title: Notifications API with PHP SDK - Invalid OAuth access token signature
body: <p>I am trying to send notification to one of my users but I have a error</p>
  
  <pre><code>[error] =&gt; Array
              (
                  [message] =&gt; Invalid OAuth access token signature.
                  [type] =&gt; OAuthException
                  [code] =&gt; 190
              )
  </code></pre>
  
  <p>I am using this code:</p>
  
  <pre><code>$token_url =    "https://graph.facebook.com/oauth/access_token?" .
              "client_id=" . APP_KEY .
              "&amp;client_secret=" . APP_SECRET .
              "&amp;grant_type=client_credentials";
  
  $app_token = file_get_contents($token_url);
  
  $params = array(
      'href' =&gt; APP_URL,
      'access_token' =&gt; $app_token,
      'template' =&gt; 'ble ble ble'        
  );
  
  $result = $facebook-&gt;api('/me/notifications/', 'post', $params);
  </code></pre>
  
  <p>$app_token return -> access_token=273347866145980|gIdxLQBHtPEHPf1Bjnw2MtnOqfA</p>
  
  <p>What am I doing wrong?</p>
  
  <p>Maybe someone knows the solution?</p>