when I add product kits buying price/selling prices always 0$. where can make it automate calculate or manual change. In case it 0 like that margin report will be 100%. It is not usable.
Dollibar v 16.0.1
I’m sorry, but I think you are missing some words that would make it clear what you are asking for/about.
What I mean is "Why Minimum buying price is 0 ? " in picture
aha, now makes much more sense to me 
But I am afraid that I can not answer why.
