We cannot confirm whether or not this is a bug unless we have a project that demonstrates this. We cannot get all the information we need just from a stack trace. If you need further assistance with this, I will ask that you provide us with a small working project that reproduces the error, so that we can take a look.
As I mentioned in another ticket of yours earlier today, we suggest you do not use the old RadChart for new development, but use the new RadChartView.
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