I am using Auto discover service Url for a specified e-mail address.
ExchangeService Service = new ExchangeService(ExchangeVersion.Exchange2010);
Service.Cr
I'd recommend that you verify that autodiscover is actually setup in DNS. The following article explains how to set it up in more detail and it also gives you information on how to test it with the Microsoft Remote Connectivity Analyzer.http://www.petri.co.il/autodiscover-configuration-exchange-2010.htm