In RadControls for ASP.NET AJAX Q1 2008 there is a change in the Client-Side API. The compatibility layer which was used in the transition beta period is now removed. All client-side methods strictly follow the ASP.NET AJAX conventions and are lower case.
For instance: get_collapsed()
should always be used from now on, get_Collapsed() is no longer supported. This also results in significant improvement in page loading times.
Please, refer to the Client-Side Programming section
in the online documantation of RadControls for ASP.NET AJAX for more details.
The Telerik team