your trying to send post commands to vBulletin, by default it blocks them from all hosts except from it's own root. That message says that vbulletin is blocking posts from that url, try adding it. If that doesn't work then I'll try to help you figure it out, but I'm betting you that's what it is.

OHHHH i see what you mean, it is blocking it because the root is different.
So try the root from the main site.. i'll try it.!!