How to flavor mint candy

I recently used an uncooked fondant recipe to make mint candy. The recipe is like a butter frosting recipe but with more powdered sugar. I flavored the candy with mint extract and I thought it tasted pretty good. A couple of weeks later the candy has no flavor. What happened to the mint? The mint extract I used was a few years old. Is this the problem? Or is there something a person needs to do to keep the flavor in mint candy? Thanks for any thoughts or help with this.:confused: