If you are using ajax, try to disable it and see if the problem persists. Please make sure that you are registering your script correctly.
Can you confirm that you are following the described steps in this article and the corresponding demo:
I have tried a scenario resembling yours with a little different approach and everything is fine on my side. Attached you will find the aforementioned sample.
If the problem remains please open a support ticket and send us the full markup of the page as well as the related code behind. Thus we will be able to further research on the problem and do our best to provide a proper solution.
the Telerik team
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