I spoke with PayPal Tech Support after talking to several other people and then sitting on hold for a looooong time. The tech support person said that while the "Set Express Checkout" API call is going to the "correct endpoint", either the "Get Express Checkout Payment Detals" or the "DoExpressCheckoutPayment" API call is going to the wrong endpoint possibly a sandbox.
The net-net to me is that it doesn't work and I'm caught between WebAssist and PayPal Tech Support.
TM