The provided code snippet is tested locally and it works just fine. If this is not your case, it will be best if you can open a support ticket and send us a simple running project
(incl. your custom skin, CSS, images, DB backup if needed and so on) demonstrating the problem (and step-by-step instructions on doing so). In that way we can reproduce and pinpoint the problems you're facing on our side, understand the logic of your application and provide a solution.
All the best,
the Telerik team