PBIS: Does it work?

I have been the chair of PBIS for 4 years.  We scored a 97% for our implementation of PBIS at my school, but still have failed to reach some of the kids.  How do we get better buy in?  Many kids are excited about our activities like dances and the student staff basket ball game, but some do not seem to care no matter what.  How do we reach that 3 percent?