Update User Field

[FatalBreeze]

Hi guys, in my forums, every user which gets to 150 posts, recieves a gift. so i wanted to build this function, i figured that in order to do so i have to have a look in functions_newpost.php, so i went there and then i figured i need to create a plugin for "newpost_complete".
actually what i want is to run a query every time a user reaches 150 posts.

so that's the code i entered:

PHP Code:

if($vbulletin->userinfo['posts'] == 150) {
    //query here
} 


the only problem is that it doesn't work...
can you help me? thanks.