Get enclosure fields from RSS with XmlNodeList

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C#

I'm trying to make an app for Windows Store get RSS feed from a web site. Here is the RSS source:

<title> some data </title>
<description> some desc </description> 
<link>http://www.****.com</link>
<pubDate>Fri, 21 Jun 2013 19:30:48</pubDate>
<guid>ttp://www.****.com</guid>
<enclosure url= "http://www.***.com//images/332010.jpg " length="5000" type="image/jpge"/>

And the code to read from it:

XmlDocument RSSXml = await XmlDocument.LoadFromUriAsync(new Uri(uri));
XmlNodeList xmlUrl = RSSXml.GetElementsByTagName("enclosure");
XmlNodeList RSSNodeList = RSSXml.SelectNodes("rss/channel/item");
StringBuilder sb = new StringBuilder();
foreach (var RSSNode in RSSNodeList)
   {
        var RSSSubNode = RSSNode.SelectSingleNode("title");
        string title = RSSSubNode != null ? RSSSubNode.InnerText : "";
        RSSSubNode = RSSNode.SelectSingleNode("link");
        string link = RSSSubNode != null ? RSSSubNode.InnerText : "";
        RSSSubNode = RSSNode.SelectSingleNode("enclosure");
        string desc = RSSSubNode != null ? RSSSubNode.InnerText : "";
    }
Label.Text = sb.ToString();

It all works fine expect for "enclosure" value, I need to get the "url" value and I tried a lot of formats but didn't get any thing and some times get errors. Any help.
Note 1 : There is no System.ServiceModel.Syndication in W8 store apps it just Windows.Web.Syndication and this one doesn't accept XmlReader.Creat(uri) as param.