Thanks Poco2013 !
your right, building material UNDER unother element can't operate formulas, you are using element schedule that's why it works,
So, th best way , is to extract material from the composite, it's possible and that's a powerfull option in archiCAD, and do the join in excel, that's easier,
Just one thing;
* Element schedutle : to schedule elements like wall, slab (calculate area of a wall , a slab area etc )
* Component schedule : to list components of an element : Components of a composite wall with all their data, components of a curtain wall, stair, railing... like listing subcategories
* Surface schedule : only for painting work, it liest the surface , and here the difference : i can build a wall with stucco , and paint it half RED and half BLUE
==> stucco quantitie : From component schedule
painting quantities : From surface schedule