Group Manager Problem

Hey guys, so I run a prison server and i use group manager as my rank system and it works great but whenever your rank up it shows the gm message saying "You have been move to the group Cprisoner' and i want to remove that text but i cant find it anywhere in the config. Its not my rankup plugin either. I also thought it could be because i was opped so i had someone else try and they got the same thing. Any Help?