Both expressions should work fine.
Are you setting the Value property of the nodes correctly? Perhaps you want to search by the node's text, in which case you have to use the FindNodeByText function.
If that isn't the case, please send the code for the page where you are trying to access the node.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed