Works great using vb4.1.3... I changed the message a little for more my own reasons using an image i made specifically for one of my sites...
http://i633.photobucket.com/albums/uu53/mansonklan/2012-03-01_131245.jpg
Very simple:
$my_banned_ids = array(8);/* Banned usergroup ids */
if (THIS_SCRIPT == 'showthread') {
if (isset($post['usergroupid']) && in_array($post['usergroupid'], $my_banned_ids)) {
$post['title'] = 'User is banned';
$post['message'] = '<img src="/images/Your image Here">';
}
}
Upload your image to forum root and put the location of image where its marked red above...