Because our RadControls for ASP.NET AJAX suite is built right on top of the ASP.NET AJAX framework, using the controls requires that a ScriptManager control also be present on the page. This is the same requirement as if you were using ASP.NET's built in AJAX controls, such as the UpdatePanel.
If you are new to using ASP.NET AJAX, I highly suggest taking a look at these great video tutorials
. If you are already familiar with these concepts, or when you get up to speed on them, take a look at our new Telerik Trainer
, which has many great videos on using our tools. Of particular interest to you might be the RadAjax video
and the RadMenu video
I hope that helps. Please let me know if you continue to have trouble.