they say aspirin helps keep flowers alive longer..what happened?

These are cut flowers you are experimenting with, right?

The baby aspirin might have something in it for flavoring which might mess up your experiment.

Other than that, I would say that your experiment gives you the answer. Of course, as with most experiments, you need to do lots of repetition to get enough data to get around stray events like, say, having one "bad" (something wrong with it that caused it to wilt earlier than the other one) flower for some reason.

Either you can consider your hypothesis refuted or you can figure out what other variable determined flower life. It could be that one of your flowers was less healthy than the other to begin with. The idea above that the aspirin was contaminated with something bad for plants is another idea.