[.NET] ArcCatalog 10.1 tree doesn't refresh after adding new custom IGxObject

I am using ArcObjects 10.1 (.NET) to customize ArcCatalog: adding new nodes in catalog tree like in the Esri's example. But when I add new child node to already expanded parent, it doesn't show up in tree. Actually, custom catalog tree node never updates again after being expanded.

Any solutions?