Why did an exception occur?

[Mohammad Dayyan]

Hi. This is my snippet code. But there is an exception in this code. How can I solve it ?

XElement xmlTree1 = new XElement("Root",
new XElement("Child1",
new XElement("Child11", ""),
new XElement("Child12", ""),
new XElement("Child13", "")),
new XElement("Child2", 2),
new XElement("Child3", 3),
new XElement("Child4", 4),
new XElement("Child5", 5),
new XElement("Child6", 6)
);

XElement xmlTree2 = new XElement("ChildNew",
new XAttribute("NAME", "mohammad"));

xmlTree1.Element("Child11").AddAfterSelf(xmlTree2);
Console.WriteLine(xmlTree1);
Console.ReadKey();

Thanks in advance .

[Howard Richards]

Your expression xmlTree1.Element() is null. Read the documentation for .Element method "Gets the first (in document order) child element with the specified System.Xml.Linq.XName." 'Child11' is not a child element of 'Root' - it's an element of 'Child1' Try this instead:

var child1 = xmlTree1.Element("Child1");
var child11 = child1.Element("Child11");
child11.AddAfterSelf(xmlTree2);

'Howard