ProSites Site Categories Image Icons not working?

Hi, sorry to be a pest. I'm trying to add image icons to my site categories for my pro sites site listings. i have the avatars plugin installed. i've tried deactivating all sorts of things to see if their interfereing but ... no luck. What's happening is this, I click the button to add an image and ... crickets ... nothing happens. i've tried it in different browsers too.

Please advise thanks.