Thank you for writing.
In order to be compliant with the data binding mechanism of RadTreeView you need to support the basic interfaces which are provided by the WinForms library, namely, the IBindingList and INotifyPropertyChanged interfaces. IBindingList is provided automatically by the BindingList class. The INotifyPropertyChanged interface must be implemented by your business objects so that RadTreeView can react on direct object changes.
In short, your custom objects must implement INotifyPropertyChanged and your private collection must be of type BindingList or it must explicitly implement IBindingList.
Please write again if you need further assistance.
the Telerik team