Another thing that occurs sometimes is that, for sanity's sake, some readers only use the 'Today's active forums' link from the main page to read what's going on. If you post a new question at 4pm, it may not get read by as many people.
I don't know what to do about that, except that I usually try to ask my new questions/post followups early in the morning. It seems to get better response. You can also 'bump' your message up if it seems to have vanished off the main page of your forum (i.e. the General forum cycles pretty quickly, so a post with 0 responses may go unnoticed if its a few days old). Keep in mind that bumping should be used judiciously, not 2 hours after your initial posting! (I know you didn't do that, it was just an example)
HTH,
David R