Default Avatar issue

In the admin panel, If I set default avatar (let say I set the avatar to “Mystery Man” in Setting – Discussion) whoever don’t have avatar, your template will automatically assign “Mystery Man” to them.

But for those who have avatar like yours, your template will not assign automatically “Mystery Man” to them.

Any idea how to solve it?

I believe with plugin, this problem will exist too, right?

My site
http://www.inspireuniversity.co