title: System.Xml.XPath.XPathException has an invalid token
body: <p>When trying to parse XML I get an exception referencing invalid tokens</p>
  
  <p>html response from the url: </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8" ?&gt;
  &lt;uclassify xmlns="http://api.uclassify.com/1/server/ResponseSchema" version="1.01"&gt;
      &lt;status success="true" statusCode="2000"/&gt;
      &lt;readCalls&gt;
          &lt;classify id="Classify"&gt;
          &lt;classification textCoverage="0.849057"&gt;
              &lt;class className="negative" p="0.567908"/&gt;
              &lt;class className="positive" p="0.432092"/&gt;
          &lt;/classification&gt;
          &lt;/classify&gt;
      &lt;/readCalls&gt;
  &lt;/uclassify&gt;
  </code></pre>
  
  <p>Code:</p>
  
  <pre><code>HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(url);
  HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse();
  var stream = myHttpWebResponse.GetResponseStream();
  var reader = new StreamReader(stream);
  string html = reader.ReadToEnd();
  XmlDocument doc = new XmlDocument();
  doc.LoadXml(html);
  string negative = doc.SelectSingleNode("/uclassify/readCalls/classify/classification/class[1]@p").ToString();
  string positive = doc.SelectSingleNode("/uclassify/readCalls/classify/classification/class[2]@p").ToString();
  </code></pre>
  
  <p>I don't really get why it isn't working. Any help would be appreciated. </p>