default credentials and ews

I have tried everything now I give up. I am able to connect to exchange web services fine using this:     Microsoft.Exchange.WebServices.Data.ExchangeService service = new Microsoft.Exchange.WebServices.Data.ExchangeService(Microsoft.Exchange.WebServices.Data.ExchangeVersion);                     service.Credentials = new Microsoft.Exchange.WebServices.Data.WebCredentials("user", "somepassword","domain");                                     service.Url = new Uri("https://tyu9site.net/EWS/Exchange.asmx");                       & ...