Do not respond to the top comment because it is the top comment. Avoid especially the urge to write your own completely unrelated comment as a reply in order to make your own more visible. This problem is generally the fault of comment systems themselves in how they allow one comment to sit at the top forever (due to age, or votes, or number of replies). In some particularly bad comment systems, the top comment, along with its replies, is the only comment visible, requiring a separate user request ("Load more comments") to view others.