Traffic Light systems for behavior management are very popular right now. Many teacher catalogs sell pocket charts designed to use this system. I myself have used this system in the classroom and found what many teachers have found, it works great... until about March.
Traffic Light Systems might seem like a positive reward system in the beginning, especially if everyone starts on "red" and earns their way to "green". However, if everyone starts on "green" and "drops a level" as a penalty for some misbehavior or misdeed then it is really a response cost system or if once students earn a level higher than "red" and then drop back down as a penalty it is a response cost system.
Some problems with response cost are that students who frequently enter into the "yellow" or "red" soon discover that this is "not so bad" and it becomes little deterrent to further negative behavior, the attention that a student receives from the act of dropping his or her level may be just enough attention to reward him or her for acting up (and ensure he or she does it again) and the "traffic light" system does little to teach or reward appropriate behavior, especially for the 80-90% of kids who are usually doing the right thing.
Think about it this way - which is more likely to get you to drive carefully and courteously the possibility of a traffic ticket (response cost) or an officer stopping you and giving you $100 for yielding in an intersection (intermittent reinforcement).
Perhaps instead of using that traffic light system as a response cost system you could use it as a classroom wide positive reinforcement, i.e. put everyone on red, including you and all the paraprofessionals. Then anytime anyone receives a compliment (decide on the rules ahead of time is it only compliments from you? from any adult? from adults and peers?) they go to yellow and then to green. When the whole class is on green the whole class gets a reward such as a party, lunch with the teacher, no homework, a trip, bring your own money to order out (BYOMOO), etc.