IMPORTANT TO NOTE FOR THOSE MEMBERS MAKING THEIR FIRST POST ABOUT POSTS NOT APPEARING AFTER YOU ENTER THEM IN A THREAD:
When a new member makes their first post and thereafter for their next few posts, the post undergoes a review by a moderator before it is approved for posting. That is why the the post DOES NOT APPEAR in the thread at first. Please be patient and allow a day or two for the the comment to be reviewed. If the post is approved, it will then appear.
Under no circumstances should you post that same comment again in the thought that this will help it appear. In fact, the opposite may happen in that the moderator will take that as a sign that you are not following proper procedure and the mod might be inclined to decline your post.
You can certainly post a different message in another thread, but you must allow for the same process to take place and the post to be approved. Eventually when you have enough posts under your belt, they will appear automatically when you post. But be aware, all posts are always subject to later review and can be deleted by any moderator after the fact if it discovered that the comment is inappropriate or violates the rules.