the <Done> of "Add Children to Tree Item" delivers "Nothing" because thats just for the Control trigger of the "Conditional Flow 2" element. The Data of the "Conditional Flow 2" comes from "Convert Record to Tree Item" and is a "Tree Item".
But in the meantime I redesigned it using the "Add Item to Tree" element (given by the "Tree Display and Management" module) and now it works. :-)
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