Do you still have the debug code on your pp_checkout_failure page? If so you should be getting the output like you did before. The last time that you tried you were getting this message:
You do not have permissions to make this API call
Are you still getting this same error? If so you may need to contact PayPal to ensure that your account is setup to allow for the Express Checkout API calls. Please post back and let us know if you are getting any other error.