Problem Binding Url to listBox.itemsSource with XElement

Im trying to make dinamically loading url in a list Box by Binding.

Inicio.xaml.cs

void cardeek_DownloadUrlCompleted(object sender, DownloadStringCompletedEventArgs e)
{
    if (e.Error != null) return;
    textBox1.Text = e.Result;
    XElement xmlUrl = XElement.Parse(e.Result);
    listBox1.ItemsSource = from url in xmlUrl.Descendants("user")
                           select new TwitterItem { Url = url.Element("card").Element("url").Value, };
}

private void ContentPa开发者_C百科nel_Loaded(object sender, RoutedEventArgs e)
{
    WebClient cardeekUrl = new WebClient();
    cardeekUrl.DownloadStringCompleted += new DownloadStringCompletedEventHandler(cardeek_DownloadUrlCompleted);
    cardeekUrl.DownloadStringAsync(new Uri("http://www.cardeek.com/wp7/response_url.php?email=" + "david.sonike@gmail.com" + "&code=" + "1"));
}

void cardeek_DownloadUrlCompleted(object sender, DownloadStringCompletedEventArgs e)
{
    if (e.Error != null)
        return;
    textBox1.Text = e.Result;
    XElement xmlUrl = XElement.Parse(e.Result);
    listBox1.ItemsSource = from url in xmlUrl.Descendants("user")
                           select new TwitterItem
                           {
                               Url = url.Element("card").Element("url").Value,
                           };
}

private void ContentPanel_Loaded(object sender, RoutedEventArgs e)
{
    WebClient cardeekUrl = new WebClient();
    cardeekUrl.DownloadStringCompleted += new DownloadStringCompletedEventHandler(cardeek_DownloadUrlCompleted);
    cardeekUrl.DownloadStringAsync(new Uri("http://www.cardeek.com/wp7/response_url.php?email=" + "david.sonike@gmail.com" + "&code=" + "1"));
}

Inicio.xaml

<ListBox Height="416" HorizontalAlignment="Left" Margin="41,191,0,0" Name="listBox1" VerticalAlignment="Top" Width="367">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal" Background="{Binding coItemBackground}">
                <phone:WebBrowser HorizontalAlignment="Left" Margin="69,140,0,0" VerticalAlignment="Top" Height="121"
                        Width="137" Source="{Binding Url}" />
            </StackPanel>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

and the Xml source in the web

www.marca.com www.elmundo.com www.vidaextra.com

In my Windows Phone 7 emulator cant see anything, anyone can help me solve the problem?¿

You are binding the Listbox to an Enumerable<TwitterItem>. As this doesn't implement INotifyPropertyChanged the UI isn't notified when you update the ItemSource in the callback.

As an alternative, consider creating an "ObservableCollection<TwitterItem> and binding to that. It automatically implements InotifyPropertyChanged so you don't need to.

You may also want to reconsider putting a WebBrowser inside the DataTemplate. There will be a performance cost of using it and it's unlikely to produce a good user experience.