Problem using wsdl, api service

I'm trying to connect to the webservice using the WSDL but run into connection problems.

I successfully added a service reference (https://reports.web.analytics.yahoo.com/api/IndexToolsApiV3.wsdl) and can browse all the available functions
But when i call the login function i get an error, "no endpoint listening".

In the config file of my application, i can see that the endpoint address is by default set to https://YWA_API_HOST/IndexTools/services/IndexToolsApiV3. I think  the part YWA_API_HOST needs to be changed, but to what?