Problem with Material Function

hey guys,
I have a little problem with material functions, i’m in the progress of rebuilding an material from a markplace demo.
Everything is woring fine expect one little issue, please check the screenshots.
I just don’t get why the material editor “in my level” is asking for a missing function input? the same construction is working fine in the marktplace demo…

I just found the issue… in the material function “metal” i had to check the “Uese prewiev value as default” in the function input node…