Yep, I'm using 2011.1.413.35 and this problem still shows up for me.
I have a support ticket open that Telerik is IGNORING. Apparently their 24 hour response time means nothing.
if a Telerik employee reads this, I'm referring to
At some point, having Tier1 email support personnel say they can't reproduce the problem gets really old. This is where having no phone support becomes a problem. I've read through everything above and there are no satisfactory solutions shown. Yes you can change all of the "telerik.web.ui" to "telerik:" but that forever makes the control uneditable by the wizards--essentially any changes that you make in the wizard (if it even runs) cause no updates back to the aspx file.
YOU GUYS CAN SEE THAT THIS PROBLEM HAS BEEN OUT THERE FOR YEARS--PLEASE FIGURE OUT WHAT THE HECK IS GOING ON...
If you denote a tone of irritation you are right. I have burned 10 hours today and tonight trying to fix this page and I am dead in the water until I can get it fixed.