Some good tips here on what to do if you are getting unexpected results with your labels. That never happens to you, right?
What to do when your label doesn't draw
So, you have just spent a few minutes deep in concentration setting up your labeling rules and applied them. ArcMap's little globe is spinning, spinning... spinning... and nothing. Several of your labels didn't draw. Panic and go to MappingCenter. Right?
There are a few things we always do when diagnosing the "where's my label" scenarios, no matter what's being labeled or what labeling engine is being used.