This is a known bug. The problem is that SelectedValue
is not updated when the selection is changed if once was set to non existing value. That is why your Validation doesn't work at all. We have already fixed the issue and it will be available in today's internal build.
Sorry for the caused inconvenience. Please let me know if you have further questions.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items