Unfortunatelly, I don't know what you are doing wrong and where to fix the error. We're investigating such kind of problems only for a fee.
The code shown is exactly the same on minibb test forums. For example, if you check this thread:
you will see that Moderator
has a 'newbie' tag (as he has less than 300 posts), but tester
has no custom tag, but custom ranking "Test Account" is written in instead. As it is defined in bb_specials.php: