There are several items to check.
First is the Avatar Upload Storage Directory or absolute path:
create the folder.
Then the folder permission should be set to 755
As Rick stated for example;
/home/vintager/public_html/images/avatar/default

Second is Full URL to Avatar Upload Storage Directory:
for the above that would be
http://www.vintageracerules.com/images/avatar/default

Once done click on the test link. if it fails go recheck for typos in the path or your folder permissions. If it passes a file will be written to the folder called test.file.

Next is the file size of the avatar.

Then you need to set permissions for the users.
Control Panel ยป Site Permissions
Can specify a remote avatar -This probably is for the ones that have a avatar now. They can just put a link to their own offsite avatar . They don't upload them to your site.

Can choose a stock avatars

Can upload an avatar -this one is where you specify who can upload

Blue Man Group
There is no such thing as stupid questions. Just stupid answers