We return this NVP/SOAP API error code when the buyer was not directed to PayPal and has not successfully authorized the transaction attempt.
Redirect the payer to PayPal after calling the SetExpressCheckout API command to complete the payment.
To learn more about identifying your Express Checkout token and redirecting your buyer to PayPal for approval, see Customize PayPal checkout pages.
See the Developer Portal for a complete list of NVP/SOAP API error codes.