When somebody answers to my question, but the answer is clearly not working, and there is no other answer, then I cannot accept an answer to my question. But since technically there is already an answer to my question, it counts to the "accept ratio" which will decrease because of this. After all, the computer can't decide whether this is a helpful answer and just calculates a ratio of two numbers.
What is the suggested way to handle this? Accept the answer although it's not working? Downvote the answer (which will hurt the poster, even if he wasn't initially aware of the situation)?