Unfortunately I am still not able to reproduce the issue in my local tests. I suggest you utilize the general troubleshooting tips from this page
(the bottom section concerning server error 500 in particular).
If the problem remains, please provide a live url where the problem can be seen or isolate a working subset of your project and send it attached to a regular support ticket. Thus we will do our best to provide up-to-point answer/solution.
the Telerik team
Watch a video
on how to optimize your support resource searches and check out more tips
on the blogs.
Follow the status of features or bugs in PITS
and vote for them to affect their priority.