title: XPath doesn't work as desired in C#
body: <p>My code doesn't return the node </p>
  
  <pre><code>XmlDocument xml = new XmlDocument();
  xml.InnerXml = text;
  
  XmlNode node_ =  xml.SelectSingleNode(node);
  return node_.InnerText; // node_ = null !
  </code></pre>
  
  <p>I'm pretty sure my XML and Xpath are correct.</p>
  
  <p>My Xpath : <code>/ItemLookupResponse/OperationRequest/RequestId</code></p>
  
  <p>My XML : </p>
  
  <pre><code>&lt;?xml version="1.0"?&gt;
  &lt;ItemLookupResponse xmlns="http://webservices.amazon.com/AWSECommerceService/2005-10-05"&gt;
    &lt;OperationRequest&gt;
      &lt;RequestId&gt;xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx&lt;/RequestId&gt;
      &lt;!-- the rest of the xml is irrelevant --&gt;
    &lt;/OperationRequest&gt;
  &lt;/ItemLookupResponse&gt;
  </code></pre>
  
  <p>The node my XPath returns is always null for some reason. Can someone help?</p>