title: Which token to use for checking payment details?
body: <p>Hello I'm am trying to integrate canvas payment to a facebook app, in my payment callback I call <a href="https://graph.facebook.com/PAYMENT_ID?access_token=APP_ACCESS_TOKEN" rel="nofollow">https://graph.facebook.com/PAYMENT_ID?access_token=APP_ACCESS_TOKEN</a> but I receive an invalid token error, in fact I don't understand which token I have to use, it's not explained at <a href="https://developers.facebook.com/docs/howtos/payments/fulfillment" rel="nofollow">https://developers.facebook.com/docs/howtos/payments/fulfillment</a></p>
  
  <p>Thanks</p>