minimum posts needed before posting in specific forum

[cyclops1]

hi all, im a new to vbulletin and i got a question. On our site we have a forum called advertise. People can advertise their site, but must have made a minimum of 50 post to post in that forum. In the forum permissions i dont see a option to specify something like that for the registered users ? Can it be done from the admin-CP or does someone know a hack ??

Ty

edit /found a solution sorry....