This sounds like it might be caused by an issue we had with checkboxes and transferring items, which was logged in as a bug:
Fixed: In client transfer with TransferMode="Move", if you check an item and then transfer it, the item.get_checkBoxElement() doesn't return the correct DOM Element
In the 2012 Q2 SP2
version of the controls this bug is fixed. Could you verify if the problem is reproduced with this version of the controls.
All the best,
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed