1. Try to register the RadAjaxManager in Sitefinity/Admin/Admin.master
Then call the RadAjaxManager in PageLoad event of the template code behind
RadAjaxManager ajaxManager = RadAjaxManager.GetCurrent(
Wrap the controls you want to update in ASP.NET Panel. There are some problems with the ajax manager and backend for 3.x. The ajax manager is loading too late so you need to move it to Admin.master as suggested.
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