I tried to reproduce the described problem by creating a RadRotator with attached handler for its ItemShown event, but to no avail. Please check the attached test sample, as well as the short demonstration clip and let me know if I am missing something. The version of UI for ASP.NET AJAX that I used is the latest one - 2014.2.724.
It is possible that the problem at hand occurs as a result of additional logic in your implementation. Please try modifying the attached sample in order to reproduce the issue. This will allow me to inspect the problem locally and to provide a more to the point answer.
If this is not possible, you could also prepare your own fully runnable sample and send it for further inspection.
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