[quote user="James Manfield"]
displays all levels in a specific reference attachment ("3D-modell") in a specific model ("Drawings")
[/quote]
James, is "Drawings" (or "Drawing" as you actually use in the code example) the name of a modelreference within "3D-modell" or the name of the modelreference in each DGN to which "3D-modell" is attached to?