Silverlight WCF Login

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class Service1
{
AirLinesEntities context = new AirLinesEntities();
[OperationContract]
public int Login(string sUserName, string sPassword)
{
    var c = (from p in context.Admins
            where p.AdminName == sUserName & p.Password == sPassword
            select p).Count();
    return c;
}

}

Login Silverlight User Control

ServiceReference1.Service1Client sc = new ServiceReference1.Service1Client();
private void btnLogin_Click(object sender, RoutedEventArgs e)
{
sc.LoginCompleted += new EventHandler<ServiceReference1.LoginCompletedEventArgs>(sc_LoginCompleted);
sc.LoginAsync(txtUserName.Text, txtPassword.Text);
}

void sc_LoginCompleted(object sender, ServiceReference1.LoginCompletedEventArgs e)
{
var c = e.Result;
if (c > 0)
{
    this.DialogResult = true;
    GlobalClass.IsLogin = true;
}
else
    MessageBox.Show("Invalid login");
}
}

MainPage

private void Link1_Click(object sender, RoutedEventArgs e)
{
Login l = new Login();
l.Closed += new System.EventHandler(l_Closed);
l.Show();
}

void l_Closed(object sender, System.EventArgs e)
{
Login loginWindow = (Login)sender;
bool? result = loginWindow.DialogResult;
if (result == true)
{
    hlbLocation.Visibility = System.Windows.Visibility.Visible;
}
}