You will be an active player (sun icon) if you play in the group often enough, given the group's own characteristics.
You will be a nearly active (clouded sun icon), semi-active (grey cloud icon) or inactive (black cloud icon) player if you play less often than that, and your ree score will be affected by this.
This can happen because you entered the group only recently (keep playing, you'll be an active player soon!) or because you've been playing less often (start playing again!).
More info on badges here.