Is it possible that you have written some client code of your own that uses this method?
It is very likely that you upgraded from a Telerik.Web.UI DLL version that is over one year old, because more than an year back in time the client-side API conventions for all Telerik RadControls were modified to better comply with the MS AJAX client-side convetions.
Currently all methods that start with get_
continue with a lower-case letter, e.g. get_zones()
Please examine your client code and fix it according to the MS AJAX conventions. If you encounter any problem please let us know.
the Telerik team