ListPickerIssue

//XAML code

<toolkit:ListPicker x:Name="listPickerCountryLogin" Grid.Row="0" ExpansionMode="ExpansionAllowed" SelectionChanged="listPickerCountryLogin_SelectionChanged" HorizontalAlignment="Left" Margin="14,43,0,0" VerticalAlignment="Top" Width="436" FullModeHeader="Select Country" Background="White" BorderBrush="White">
                <toolkit:ListPicker.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Text="{Binding Country}" Width="250" />
                        </StackPanel>
                    </DataTemplate>
                </toolkit:ListPicker.ItemTemplate>
                <toolkit:ListPicker.FullModeItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Text="{Binding Country}" Width="300" Margin="0,0,0,20" FontSize="24"/>
                        </StackPanel>
                    </DataTemplate>
                </toolkit:ListPicker.FullModeItemTemplate>
            </toolkit:ListPicker>


            <toolkit:ListPicker x:Name="listPickerCCLogin" Grid.Row="1" ExpansionMode="FullScreenOnly" SelectionChanged="listPickerCCLogin_SelectionChanged" Width="80" HorizontalAlignment="Left" Margin="14,10,0,0"  VerticalAlignment="Top" FullModeHeader="Select Country" Background="White" BorderBrush="White">
                <toolkit:ListPicker.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock Name="lblCC" Text="{Binding CC}" Width="235" />
                        </StackPanel>
                    </DataTemplate>
                </toolkit:ListPicker.ItemTemplate>
                <toolkit:ListPicker.FullModeItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal">
                            <TextBlock  Text="{Binding Country}" Width="300" Margin="0,0,0,20" FontSize="24"/>
                        </StackPanel>
                    </DataTemplate>
                </toolkit:ListPicker.FullModeItemTemplate>
            </toolkit:ListPicker>
            <Button Content="change" Grid.Row="2"  Height="200" Click="Button_Click" BorderThickness="1" />


//C# code

public MainPage()
{
 InitializeComponent();
 List<Countries> source = new List<Countries>();
 source.Add(new Cities() { Country = "ES", CC = "10" });
 source.Add(new Cities() { Country = "US", CC = "20" });
 source.Add(new Cities() { Country = "UK", CC = "30" });
 source.Add(new Cities() { Country = "MX", CC = "40" });

 this.listPickerCountryLogin.ItemsSource = source;
 this.listPickerCCLogin.ItemsSource = source;
}

private void Button_Click(object sender, RoutedEventArgs e)
{
  WebClient client = new WebClient();
  client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(client_DownloadStringCompleted);
  client.DownloadStringAsync(new Uri("http://api.twitter.com/1/statuses/public_timeline.json", UriKind.Absolute));
}

void client_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
    //var deserialized = JsonConvert.DeserializeObject(e.Result);
    Dispatcher.BeginInvoke(new System.Action(delegate()
    {
          listPickerCountryLogin.SelectedIndex = 1;
          listPickerCCLogin.SelectedIndex = 1;
    }));
}

private void listPickerCountryLogin_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
       if (listPickerCountryLogin.SelectedIndex >= 0 && listPickerCountryLogin.SelectedIndex < listPickerCCLogin.Items.Count)
          listPickerCCLogin.SelectedIndex = listPickerCountryLogin.SelectedIndex;
}

private void listPickerCCLogin_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
      if (listPickerCCLogin.SelectedIndex >= 0 && listPickerCCLogin.SelectedIndex < listPickerCountryLogin.Items.Count)
         listPickerCountryLogin.SelectedIndex = listPickerCCLogin.SelectedIndex;
}


//And finally Countries class is:

 public class Countries
    {
        public string Country
        {
            get;
            set;
        }
        public string CC
        {
            get;
            set;
        }
    }