If you're a first time poster, one of us moderators has to approve your post before it shows up. There are several that we've missed.
NOT deliberate, I assure you.
If you don't see your post after a day or two, you could try sending a private message to either me or Florian who are the most active moderators on the forum. I'll try to keep a closer eye on the Moderator's Panel. Sometimes I see a little highlighted tell tale informing me that I need to approve/disapprove a post. Sometimes I don't.