Button Question - Flash CS3


I am new here, but this site is awesome! I have a quick question regarding flash buttons. I have been learning flash myself over the past few months, and have always wondered how to limit the clickable region of a button to one point.

For example, on my site: www.meflect.net - on the product page, I have a picture that is a button and it expands to a larger version of the picture. However, you are able to click in the region that is the size of the enlarged image.

Does anyone know how to fix this? Your help is greatly appreciated!