Well...
First off, for being so short, it was too big of a file. It seems that you didn't optimize the sound.
Next, the graphics weren't that good. Kind of scratchy, that may be your style, but that's not a style that appeals to me.
Third, it's too short.
Fourth, it's not that funny. It had strong presentation, and a very high potential, but you just didn't do it as well as you could've. Suspense to the joke would've been better, like, show them getting on the elevator, show her light up the cigarette, etc.
Finally, the message isn't as good as you'd probably have liked. No matter how much you drive it into a smoker's head that it's not good for them, a comedic message will not inspire a change of heart.
Try harder next time.