I have an answer that has been voted up to a reasonable level, which I take to mean it was a positive contribution. But there has been one vote to delete. How do I figure out the reason for a vote to delete? There are no comments.
Without a comment to tell you, you don't know. All you can tell is that someone disagreed with the post, or the way it was written.
Having read the post, I would probably have to agree with the delete vote - compare your post with Dom's post, which provides a bit of explanation. Yours seems to be more of comment.