Some of the topics don't really feel like posting in, so you'll expect most of us not to post in it because it doesn't seem reasonable to post in. If you really want people to post in your topic, you need to represent yourself more better in order to be able to make a good topic. Plus, the layout of your topics/posts must be a top form or you won't get much replies since it can give different impressions from people.
That basically meaning if your font is too huge, members will think you're a noob. Maybe if you want more people to get posting in your topic, represent yourself better, plus, make us feel you exist by posting in other topics than your own. Also, some people are more into GTA IV than San Andreas now, so you'll expect that forum to be a little low on activity.
So a little tip for you mate, post in other peoples topics than your own topics, it will make you exist. Plus, get some patience. This a forum. You won't get a reply at an instant when you just made the topic.