The most likely reason for this behavior is that the
HttpHandler is not present in the web.config. These three operations are
not performed on the client and thus require
that the RadImageEditor can properly communicate with the server. The easiest approach to enable the Telerik HttpHandler is to go to the design view in VS, show the Smart Tag of the RadImageEditor
and select the Enable RadImageEditor HttpHandler option. You can also manually add the needed handlers under system.web -> httpHandlers for IIS versions prior to 7.0 as follows.