Problem z yml

Witam ma problem bo jak mam:

on load:
    if folder "plugins/core/" doesn't exists:
        send "Brak folderu core" to console
        create folder "plugins/core/"
        send "Utworzono"

to mam takie błędy w konsoli:

can't understand this condition: 'folder "plugins/core/" doesn't exists' (core.sk, line 2: if folder "plugins/core/" doesn't exists:')

Prosze o szybką pomoc :}