I have tried this twice now. I get the message about being moderated, but the thread never appears. First time I was not that worried about... can't even remember what it was. The second is more annoying as I was trying to contact Maskrider (he already had one save available and I was wanting to ask about some other cars). His email failed (via his web site) and it does not appear that he will accept PM's so I decided to post a thread. I searched and there appeared to be no similar thread.
To keep up the quality of the GT4 forum (to avoid spam and repetitive threads) we moderate each thread before it gets posted up on the board. There is the possibility that you tried to post a thread when no mods were online.
As for you maskrider thread - our GT4 board isnt for personal messages; it is bad luck you cant get hold of him via PM or email, but the GT board is for public discussion, not private