Object: Web TreeView Control

Code:
    TreeNodeType myType = new TreeNodeType();
    myType.CheckBox = true;

    myTreeView.TreeNodeTypes.Add(myType);
    myTreeView.ChildType = "myType";
I'm trying (in code) create a new treenodetype, add it to the treeview's treenodetype collection and then make the treeview use that nodetype

This does nothing to the treeview nodes, no matter if I add the nodes to the treeview before or after this code???

I'm looking for a way to make the ChildType work, as I need to write some test cases for it

Missing something?