[Konstantin Katsovich]

Попробуйте вот так, без WhoAmIRequest

result += string.Format("Caller User Id = {0}",((OrganizationServiceProxy)factory.CreateOrganizationService(context.UserId)).CallerId);

result += string.Format("User System Id = {0}", ((OrganizationServiceProxy)factory.CreateOrganizationService(null)).CallerId);