I flagged this answer because it was inaccurate and provided incorrect information, but my flag was rejected. Here's a screenshot.
I'm not sure why the flag was declined, as I was indicating the answer as a wrong answer. Can someone tell me why?
There isn't a "wrong answer" flag for a reason. As the response says, "flags should not be used to indicate technical inaccuracies, or an altogether wrong answer".
If you see an answer you believe is inaccurate or incorrect, there are plenty of things you can do. You can downvote it, you can comment on it to explain to the answerer and viewers that you think it's wrong, or you can post your own answer or upvote correct ones.