I wrote "Der er ingen historisk bevis". Why intet instead of ingen?
because it's et bevis
So there is no -t form for historisk (and other -isk adjectives)?
can anyone explain to me why "der er ikke historisk bevis" is wrong?
"ikke" negates a verb while "intet" and "ingen" negate an object. You would be using "ikke" if the sentence would be something like "There isn't a / any proof."
Either you're wrong, or Duo is wrong, 'cause det er ikke historisk bevis was accepted for me.