I don't like such kind of questions on Meta, so I will try to make it a good question and describe all with a details.
Today I down-voted https://stackoverflow.com/questions/7469685/what-could-be-a-replacement-for-swf-movie-to-present-a-video-on-browser added a comment with explanations why I down-voted it, and flag it as non constructive (my flag was marked as helpful). An hour later one of my answers was downvoted, without any comment left about the reason. Yes, that wasn't my best answer, but in my opinion it answers the question. Well, even if somebody considered my answer incorrect he could add the correct answer, or up-vote the competitive ones. I checked the users reputation who made competitve answer, and he didn't get any rep today for that answer.
It was my second down-vote on Stack Overflow, so I was a little bit down, after that. I think who could considered my answer so completely wrong, and that I thought that maybe it was revenge down-vote. So I checked reputation of the user I down-voted today, and it was clear that he down-voted some answers today. After I checked that that user cast only 19 downvotes in 8 months, so chances were very big that this was revenge down-voting.
I came to this meta, and searched what I should do in this case. I found that most questions about down-votes, were closed as duplicates. After I found Victim of Revenge Downvoting, and found that a team member of Stack Exchange suggested to cast a flag for moderator attention, and explain the situation there.
I did that, and create next flag:
I think after I down-voted this question (and a comment about this), the OP down-voted me in revenge; it's clear from his today's reputation and from timing of my down-vote of his question, and time when one of my answers was downvoted. I cannot be 100% sure about that, but if somebody can check this, and point him that it's not the good way to do.
As you can see, I didn't ask for returning any reputation, or banning that user, I just wanted, somebody to point him, that he did wrong. And after I get this respons on my flag: "declined - flags should only be used to make moderators aware of content that requires their intervention." So in the end I also lost 10 points of the flag weight.
After describing all situation in details, I want to know were exactly I was wrong here. And what should I do next time something like this happens?