Accessing ASP.NET WCF Authentication Service in Winforms Application

Hi.
I'm trying to use ASP.NET WCF Authentication Service from a Winforms Application.
I am referring to this article as a tutorial.
for silverlight clients, the WCF Auth service works well.
but for Winforms Apps,
private void employeeLogIn_Click(object sender, RoutedEventArgs e) { AuthenticationServiceClient client = new AuthenticationServiceClient(); client.ValidateUser("employee", "mypassword", null) // return true client.Login("employee","mypassword", null, true) // returns true. client.IsLoggedIn() // and it returns FALSE. why? }
the AuthenticationServiceClient.IsLoggedIn() always returns false even after login.
...