"Let's go to Korea every day."
Translation:매일 한국에 갑시다.
In a previous question, I used "오늘은" for "today" and it was marked correct. Here I used "매일은" for "every day" and it was marked incorrect. I know "오늘은" is common, and "매일은" is a little awkward to say and therefore not so common, but it is grammatically correct, yes? Or am I missing something subtle here?