It should be a gif if you want it to animate, I'm fairly sure. :yesyes:
Then it should work, along with being under 80x80 and 19.5 kb.
When my gif's didnt work it was because the file size was too big, your problem is probably more to do with it being a jpg.
For resizing, I used GIMP(it's free). That kept it as an animation, while resizing through internet sites caused it to lose the animation for some reason.