"That is not correct!"
Translation:Det stämmer inte!
"correct" in English is an adjective here, and while Swedish can say det är inte korrekt (which is also accepted), there's a more idiomatic version.
The better option is to used stämma, which is a verb meaning "to be correct". Essentially, it's like saying "that corrects not" in English - if English had been able to use the word like that.
Finally, "that" can translate into either det or det där in Swedish. So that's why you get det där, and the above is why you don't get an är.