Flash Actionscript help

Hi! I am working on a flash movie of a map. When you scroll over the city star I want it to change to a different color star and then when you click on it it pops up with a ballon with the city name and such information that you can select to learn more. I have it working to switch out images when you roll over however I can not get the ballon to pop up when you click. (make sense?) I have used a movie clip and with several keyframes and using the roll over and hit. When I use the script: on (release) {gotoAndPlay(4);}. I am getting an error when I test scene but it is blank not telling me what the error is. Any suggestions? all halp is very much appreciated!!

Duckie