循环中AppendChild(1)的值添加不了，而AppendChild(0)和(2)却能添加。解决办法

循环中AppendChild(1)的值添加不了，而AppendChild(0)和(2)却能添加。。。。。。..................。。。。。。。。。
bookstore.xml:

XML code

<?xml version="1.0" encoding="utf-8"?><bookstore>  <book genre="fantasy" ISBN="2-3631-4" old="29">    <title>Oberon's Legacy</title>    <author>Corets, Eva</author>    <price>5.95</price>  </book>  <applenote genre="fantasy" ISBN="2-3631-4">    <title>Oberon's Legacy</title>    <author>Corets, Eva</author>    <price>5.95</price>  </applenote>  <book genre="fantasy" ISBN="2-3631-6">    <title>Oberon's Legacy</title>    <author>Corets, Eva</author>    <price>5.96</price>  </book>  <book genre="fantasy" ISBN="2-3631-6">    <title>Oberon's Legacy</title>    <author>Corets, Eva</author>    <price>5.97</price>  </book></bookstore>

C# code

            XmlElement xe1 = xmlDoc.CreateElement(childNodeName);//创建一个节点            parentNode.AppendChild(xe1);//添加到父节点节点中             for (int i = 0; i < tmpXe.Count; i++)            {                xe1.AppendChild(tmpXe.Item(i));//将临时节点添加到新元素中                xmlDoc.Save(xmlFile);            }