[15.18] Can not research Mining Productivity 15

[nick5337]

factorio 0.15.18

I have tried to research the the mining productivity 15 twice now, and never got it.
(Not sure it is the right name cuz i play on danish languege and don't know how to change it)

[Koub]

What happens when you try ? can we have some screenshots ? maybe a savegame ?