So "ip-address" is now the IP address of the recorder and "portnumber" is the port number of the recorder.
In your URL, you record http://ip-address:portnumber/basepath
You don't want to have the base path in the recorder, because your application is appending basepath to the URL. Perhaps you've replaced too much of your real URL with the virtual URL? It's designed to be able to drop-in the virtual service in place of the real service, so your environmental configuration should be to replace hostname and port number, but leave everything else the same, just like what would happen when moving between different pre-prod environments. The DevTest recorder for HTTP is a gateway / proxy device, so it captures *all* HTTP service calls between the pieces of architecture in-scope and those out-of-scope.
http://real-backend-ipaddress:real-port/myBasepath becomes
http://virtual-backend-ipaddress:virtual-port/myBasepath
Rick