You should make sure that the \App_GlobalResources\RadEditor.Main.resx file contains a ClearClass name value. For your convenience I have attached the latest Q3 SP1 version of RadEditor.Main.resx file which you can use.
If you still experience any problems, please open a support ticket and send a sample working project that demonstrates the issue. I will examine the project, find the problem and provide a solution after that.
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