mipson;
I'm sure that some others will hop on in with a suggestion or two, but here are my thoughts....
First, your students should not be shouting out rule reminders to anyone. It should be led by you, chosen by you, at a time, tone, and volume chosen by you. If you want to remind the class of the rule, just call out, "Rule #" and have the kids reply with the rest of the prompt. It sounds like your class is now looking to add to the disruption by calling out the rule reminder and therefore, feel they shouldn't be corrected themselves! Wrong! I would suggest going back in Monday and stating that it is you, and only you, who is the rule reminder. Anyone shouting out rule reminders other than you will earn you, the teacher, a point on the scoreboard. Also remind them that your classroom is to be a positive experience/environment for everyone and any member who does not honor that idea, is themselves, a rule breaker (Rule above all rules: Respect Everyone!) and may need practice of THAT rule!
Second, is it truly just one student who is breaking the rule(s) all the time? If so, how long have you been using the Scoreboard only? What grade? It may be time to break out the practice cards and give those particular rule breakers an opportunity to practice the rule(s). Do you feel that this is deliberate rule breaking? If not, practice is definitely the way to go (and even if it is deliberate, I'd try practice cards first before going the next step...)
Third, I'd suggest you try to meet with the rule-breaking/offended student(s) outside of class time and talk to them about their feelings, their perspective of the "problem", and what you, as their caring teacher, can do to help them be more successful with the rules. Let them know you are on their side, you know they can succeed, and you are there to help them do it. You will be amazed how much a listening ear, an open door policy, and a little compassion and grace will impact your students, at least it seems to work for mine (inner city, disadvantaged, single parent home, troubled MS youth). You may find out very helpful information as a result of your friendly conversation with these kids - perhaps a seat change is in order, there are other students who set the offender up to fail (through negative comments etc), or there are other issues you didn't know about previously.
Fourth, remember this: WBT is all about the long-term big picture. Yes, you need to know, understand, and even respond to the daily details (like this situation), but you also need to keep in mind the big picture. Keep doing what you are doing. Re-read the WBT materials, read the additional information here on the forum, and remember that with WBT, you have all the information and strategies you need to be successful. Hang in there, and keep us up to date with how it's going in your classroom.