Combobox + movieclips = headache

I’ve been racking my brain on this for several days…

I have a US map and a combobox component with the names of all 50 states.
I’ve painstakingly made an invisible button over each state that when clicked will pull up data about the state from an XML file and shoot it back out on stage. (combobox does the same thing)

On a seperate layer I’ve made 50 Movieclips(one for each state)that just highlights the selected state in a dif. color when chosen.

How do I make these movieclips only highlight(become visible)when the selected state has been chosen? Any help on this is greatly appreciated =)