Games: Keeping Score

So I wrote the code out to keep score in my Flash Game I am creating for Class. However, when I click on the button it just keeps adding 100 so instead of it being 100, 200, 300 points it just continues to list 100 over and over again. For example, 100100100100100. I am not sure how to fit this. I did it correctly once in a different tutorial but when I tried to do it on my own that happened. Any suggestions?