As you recall, I’ve started writing about ASP.NET AJAX during preview 5. Meanwhile, preview 6 was out and there were some changes which might break your code. One of the things which changed is the in which way you indicate controls and components declaratively.
With preview 5, you’d use only a string which identifies the ID of the control or component. From preview 6 onwards, you’re supposed to use # prefix to indicate an HTML element search by ID and $ prefix to indicate that you’re searching a MS AJAX component by ID. I’ll try to update the samples I’ve published, but the truth is that, currently, I’m really busy and don’t really know when I’ll have the time to update them. So, if you something doesn’t work for you, take this into consideration and start playing with the new prefixes.