Could you confirm that you are experiencing this problem outside DNN. You can use our online demos for testing: http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx
. Otherwise please note that version 5.0 or later of DNN uses the Professional provider of RadEditor, which is implementation of the DotNetNuke developers and it is not supported by Telerik. That is why my suggestion is to post your question in the DNN forums or contact the support of DNN for help.
All the best,
the Telerik team
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