Using the above, you would have to have an avatar "pre-made" for each user with each ID, otherwise it will not auto-***ign and avatar to them (which honestly, would be a pain if you have more than a few members

).
I would suggest just letting them choose their own avatar is they want, but if you want them all to have an avatar, I think there is a small "one-line" hack that will show a default one (of your choice) until they choose their own.