title: DoExpressCheckoutPayment or /execute transactions are always pending. Why?
body: <p>When I integrate PayPal with my sandbox test account, all transactions I create via the <code>DoExpressCheckoutPayment</code> API call, or PayPal's new <code>/execute</code> REST call are pending and I have to manually accept them, or I have to wait 3-5 days. Why?</p>