title: Adding a child node to XML in flex
body: <p>In a Flex application, I'm have an xml object that I'm binding to a tree control.  I'm able to add a child node to the xml but when I try to add a child to the child node it doesn't appear on the tree control</p>
  
  <pre><code>tree =  &lt;node label="Root"&gt;
                          &lt;node label="Category 1"/&gt;
                          &lt;node label="Category2"/&gt;
                          &lt;node label="Category3"/&gt;
                          &lt;node label="Category 4"&gt;
                              &lt;node label="SubCategory4.1"/&gt;
                              &lt;node label="SubCategory4.2"/&gt;
                          &lt;/node&gt;
                      &lt;/node&gt;;                    
              var someNode:XMLNode = new XMLNode(9, 'Category5');         
              var aSubNode:XMLNode = new XMLNode(9, 'SubCategory5.1');
              someNode.appendChild(aSubNode);                                 
              tree.appendChild(someNode);
  </code></pre>
  
  <p>So Category5 appears on the tree control but SubCategory5.1 does not. What am I missing?</p>