Auto-Assign Prefix when a new reported post is made

[CoffeeLovesYou]

Hello,
I am trying to auto assign a prefix to a new reported post thread when it is automatically created.
Here is the code I am trying to use (Thanks Lynne and the other user who's code I found on here)

if($foruminfo['forumid'] == 51){
$vbulletin->GPC['prefixid'] = 'report_status_response';
$newpost['prefixid'] =& $vbulletin->GPC['prefixid'];
}

51 is our reported posts forum.
report_status_response is the prefix ID I am trying to have auto assigned to a new reported post thread.
I had this plugin hooked to newthread_post_start

Thanks!