Mad I researched question and provided answer thinking I was helping out by answering one of the many posts with no answer; I shouldn't have taken my time.
We see the same question asked many times. Some people don't think about using the seach feature for topics, and other times perhaps they think their is more recent information available than on a previous post.
While we appreciate people responding to questions to they know the answers too. We don't appreciate the attitude of mocking posters because they felt the questions were repeated too often, or posted in the wrong spot.
If you know the answer to a question, respond if you like, and forget the etiquette lecture. Otherwise no need to post at all.
Though you may have answered the poster's query, this type of attitude is likely to ensure they don't return to the site to ask any other questions they have.