title: get node value from string xml
body: <p>I have this string XML </p>
  
  <pre><code>string innerXml = @"&lt;detail&gt;&lt;WCFFaultExcepcion xmlns=""http://schemas.datacontract.org/2004/07/CIEL.DigiturnoMega.Entidades"" xmlns:i=""http://www.w3.org/2001/XMLSchema-instance""&gt;&lt;ErrorId&gt;b7e9d385-9118-4297-baca-db9ab00f3856&lt;/ErrorId&gt;&lt;Message&gt;Índice fuera de los límites de la matriz.&lt;/Message&gt;&lt;/WCFFaultExcepcion&gt;&lt;/detail&gt;";
  </code></pre>
  
  <p>This is the stringXML</p>
  
  <pre><code>&lt;detail&gt;
      &lt;WCFFaultExcepcion xmlns="http://schemas.datacontract.org/2004/07/CIEL.DigiturnoMega.Entidades" xmlns:i="http://www.w3.org/2001/XMLSchema-instance"&gt;
          &lt;ErrorId&gt;b7e9d385-9118-4297-baca-db9ab00f3856&lt;/ErrorId&gt;
          &lt;Message&gt;Índice fuera de los límites de la matriz.&lt;/Message&gt;
      &lt;/WCFFaultExcepcion&gt;
  &lt;/detail&gt;
  </code></pre>
  
  <p>What I want is to get the value of the detail Tag, I’m trying with this example but all return null o cero count, could you help me?</p>
  
  <pre><code> private static void Example()
          {
              string innerXml = @"&lt;detail&gt;&lt;WCFFaultExcepcion xmlns=""http://schemas.datacontract.org/2004/07/CIEL.DigiturnoMega.Entidades"" xmlns:i=""http://www.w3.org/2001/XMLSchema-instance""&gt;&lt;ErrorId&gt;b7e9d385-9118-4297-baca-db9ab00f3856&lt;/ErrorId&gt;&lt;Message&gt;Índice fuera de los límites de la matriz.&lt;/Message&gt;&lt;/WCFFaultExcepcion&gt;&lt;/detail&gt;";
  
              XmlDocument doc = new XmlDocument();
              doc.LoadXml(innerXml);
  
              XmlNode node = (XmlNode)doc.DocumentElement;
              XmlNode optionalNode = node.SelectSingleNode("/detail/WCFFaultExcepcion");
              XmlNode optionalNode1 = node.SelectSingleNode("detail/WCFFaultExcepcion");
              XmlNode optionalNode2 = node.SelectSingleNode("/detail/WCFFaultExcepcion/ErrorId");
              XmlNode optionalNode3 = node.SelectSingleNode("detail/WCFFaultExcepcion/ErrorId");
              XmlElement optional = doc.SelectSingleNode(@"/detail/WCFFaultExcepcion/ErrorId") as XmlElement;
              XmlElement optiona2 = doc.SelectSingleNode(@"detail/WCFFaultExcepcion/ErrorId") as XmlElement;
              XmlNode xNode = doc.DocumentElement.SelectNodes("ErrorId")[0];
              XmlNodeList xnList = doc.SelectNodes("/detail/WCFFaultExcepcion");
              XmlNodeList xnList1 = doc.SelectNodes("detail/WCFFaultExcepcion");
              XmlNodeList xnList2 = doc.SelectNodes("/detail/WCFFaultExcepcion/ErrorId");
              XmlNodeList xnList3 = doc.SelectNodes("detail/WCFFaultExcepcion/ErrorId");
          }
  </code></pre>