Conditional Formatting not Working on Data Validation Cell

This seems like something that should be working fine, but clearly I'm missing something. I am doing up a seating chart for an office. Each area needs to have a certain number of people that have certain classifications. I'll just use one "seat" as an explanation. Cell B7 says "1", representing seat 1, nothing special. Cells B8 and B9 pull from a Data Validation List of employee names, and is using Merge and Center and Wrap Text. Cell B10 represents the employee class, for example "EXC", which pulls from another Data Validation list. What I want to happen, is when the employee class is selected as "EXC", that cell, along with the employee name cells (so cells B8, B9 and B10) all turn green. My conditional formatting says B10="EXC", format is set as green fill and the applied field is $B$8:$B$10. When it is applied, only the employee name cells (B8 and B9) turn to green. The class cell (B10) remains normal. I cannot figure out what the problem is, and it's driving me nuts because this should be extremely simple. I have also tried using a formula similar to if(B10="EXC",1,0), but had the same results. Thanks!