If your post is private you must also explicitly include the group in the post permissions (to allow the forum "contact" to see the post) **and** mention it in a tag (which redistributes the post to the forum members).
Posting privately to a public forum, will result in your posting being displayed on the forum wall, but not on yours.
+Additionally it is possible to address a forum with the exclamation mark.
+In the example above this means that you can address the bicycle forum via !bicycle.
+The difference to the @ is that the post will only be sent to the addressed forum.
+This also means that you shouldn't address multiple forums in a single post in that way since it will only be distributed by one the forums.
+
You may also post to a community forum by posting a "wall-to-wall" post using secure cross-site authentication.
Comments which are relayed to community forums will be relayed back to the original post creator.