According to your account you do not have any licence. You should ask the licence holder to add you as a licence developer and you will be able to use our support system not only our forums which are available for everyone.
To your question: I'm not sure how it is related to RadGridView. Do you see any difference in your case between RadGridView and the standard Silverlight DataGrid when you have CheckBox in the column CellTemplate?
the Telerik team
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