title: Xpath error has an Invalid Token
body: <p>I have the following C# code:</p>
  
  <pre><code>var selectNode = xmlDoc.SelectSingleNode("//CodeType[@name='" + codetype + 
      "']/Section[@title='" + section + "']/Code[@code='" + code + "' and 
      @description='" + codedesc + "']") as XmlElement;
  </code></pre>
  
  <p>when I run my code it raises the error saying "the above statement has an invalid token"</p>
  
  <p>These are the values for the above statement.</p>
  
  <pre><code>codeType=cbc
  section="Mental"
  codedesc="Injection, enzyme (eg, collagenase), palmar fascial cord (ie, 
      Dupuytren's contracture"
  </code></pre>