I guess you're experiencing this problem because you're using a List to store your Children elements. When you bind something to a collection and you want to be able to change the items in this collection dynamically (note that I said the Items, not the collection itself, the PropertyChanged() event will help you if you change the whole collection(its reference), not when you change its items) you should use a collection the implements the INotifyCollectionChanged interface. I think that the only build in collection which implements this interface is the ObservableCollection, so you should always use it when you use bindings.
I've created a sample project so could you please examine it and if you have further questions feel free to ask.
the Telerik team
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