private void StartLogin()
{
// Disable the button
this.LoginButton.IsEnabled = false;
// Init ModelProvider
ModelProvider mp = ModelProvider.Instance;
mp.Clean();
mp.UserId = UserNameTextbox.Text;
mp.Password = PasswordTextbox.Password;
// TODO: remove below in released version
//mp.UserId = @"*****@*****.**";
//mp.Password = @"beelun";
this.NavigationService.Navigate(new Uri("/LoadingProgress", UriKind.Relative));
}