XML Parsing Error in Window Phone - silverlight

Question

I'm creating a tweeter example in window phone and got NullReferenceException
I think it might be that the syntax is incorrect on the right side of the expression but couldn't tell what and why..
Anyone has an idea why this resulted in error?
.xaml.cs:
public partial class MainPage : PhoneApplicationPage
{
// Constructor
public MainPage()
{
string url = "http://api.twitter.com/1/statuses/user_timeline.xml?screen_name=noradio";
WebClient twitter = new WebClient();
twitter.DownloadStringCompleted += new DownloadStringCompletedEventHandler(twitter_DownloadStringCompleted);
twitter.DownloadStringAsync(new Uri(url));
}
void twitter_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error != null)
return;
XElement xmlTweets = XElement.Parse(e.Result);
listBox1.ItemsSource = from tweet in xmlTweets.Descendants("Status")
select new TweeterItem
{
ImageSource = tweet.Element("user").Element("profile_image_url").Value,
Message = tweet.Element("text").Value,
UserName = tweet.Element("user").Element("screen_name").Value,
};
}
.xaml:
<ListBox Height="521" HorizontalAlignment="Left" Margin="0,131,0,0" Name="listBox1" VerticalAlignment="Top" Width="476">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Height="132">
<Image Source="{Binding ImageSource}" Height="73" Width="73" VerticalAlignment="Top" Margin="0,10,8,0"/>
<StackPanel Width="370">
<TextBlock Text="{Binding UserName}" Foreground="#FFC8AB14" FontSize="28" />
<TextBlock Text="{Binding Message}" TextWrapping="Wrap" FontSize="24" />
</StackPanel>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>

Answer 1

I usually do something like this, then I can check the values for null afterwards:
XmlReader xmlReader = XmlReader.Create(e.Result as Stream);
while (xmlReader.Read())
{
if (xmlReader.NodeType == XmlNodeType.Element)
{
switch (xmlReader.Name)
{
case "profile_image_url":
ImageSource = xmlReader.ReadInnerXml();
break;
case "text":
Message = xmlReader.ReadInnerXml();
break;
case "screen_name":
UserName = xmlReader.ReadInnerXml();
break;
}
}
}