I use .Net, and Visual Studio 2010.
I downloaded the WSDLs and corrected the maxOccurs error, and adding the WSDL as a Web Reference works just fine.
The problem occurs when I call SetExpressCheckout. The error simply says, Version is not supported. I have checked the version of the WSDL, which is 76.0 - and should be correct AFAIK.
The Web Service endpoint being used is this: https://api.sandbox.paypal.com/2.0/
Is there anywhere I need to specify the version, or is the service endpoint being used wrong?