关于C#读取XML有关问题

        private void InitList()
        {
            XmlDocument xml = new XmlDocument();
            xml.Load("../../XMLFile1.xml");
            XmlNode x = xml.DocumentElement;

            foreach(XmlNode xx in x.ChildNodes)
            {
                tv t = new tv();
                t.TvName = xx["tvName"].InnerText;
                t.TvType = xx["tvType"].InnerText;
                foreach(XmlNode xxx in xx.ChildNodes)
                {
                    if (xxx.Name == "programs")
                    {
                        foreach (XmlNode xxxx in xxx.ChildNodes)
                        {
                            String s = xxxx.InnerText;
//此处要是使用索引器就会报错 如 s = xxxx["ProgramName"].InnerText;
                            //未将对象引用到实例 ...很费解.
                            t.ProgramName.Add(s);    
                        }
                    }
                } 
                list.Add(t);//存储tv实体类的泛型集合
            }
        }

<?xml version="1.0" encoding="utf-8" ?>
<tv>
  <tvProgram>
    <tvType>黑白</tvType>
    <tvName>北京电视台</tvName>
    <programs>
      <ProgramName>认错</ProgramName>

    </programs>
  </tvProgram>
  <tvProgram>
    <tvType>RGB</tvType>
    <tvName>南京电视台</tvName>
    <programs>
      <ProgramName>认错</ProgramName>

    </programs>
  </tvProgram>
  <tvProgram>
    <tvType>彩色</tvType>
    <tvName>东京电视台</tvName>
    <programs>
      <ProgramName>认错</ProgramName>

    </programs>
  </tvProgram>
</tv>