Can't add portrait

I'm trying to add a new user picture or avatar or portrait or whatever you call it to my profile, but it just doesn't seem to work...!?! I've tried it with Safari, I've tried it with FireFox 3 -- no succes...! I've tried de-activating ad-blockers and what not...it just doesn't work...!

When I click on the large blue button to choose a picture nothing happens...! What's up with that...?!