通过XML Attribute在ASP.Net TreeView中扩展节点

I have a ASP.Net TreeView control that I am binding to an XML data source. I'm wanting to be able to control which nodes are expanded and which ones are collapsed in the XML definition file. The Expanded='' doesn't work for me though. In the following simple example, I want Node 2 to be fully expanded.I have a ASP.Net TreeView control that I am bin