I was reading a question and I accidentally upvoted an answer by mistake (i wanted the answer below it). The answer already had 1 up vote so when I upvoted it went to 2. I realized I made a mistake and then down voted to take away my vote for that answer. BUT, the votes went to 0 instead of 1 and I was penalized points for down voting and of course the user who posted the answer now has -2 points.
Is this a bug or did I do it wrong?