MongoDB增量查询无法按预期工作

I am trying to increase post's comment vote in atomic operation so I am trying to upvote post's comment if current username is not exist in DownVoters and UpVoters list of comment.But below query really strangely sometimes works but not always. I have checked that username is not exist in DownVoters and UpVoters list but still below query does not work. What is wrong at below query ?I am trying to increase post's comment vote in