We upgraded to Telerik.WinControls  2012.2.726.20
I tried adding a RadTreeNode as follows
RadTreeNode rtn1 = new RadTreeNode("C1");
rtn1.CheckType = CheckType.RadioButton;
rtn1.CheckState = Telerik.WinControls.Enumerations.ToggleState.On;
received an error when running.
		