you have the most up to date flash.  you need to be using the older version of flash.   Its a pain, I agree, but its the only way.  Try using Internet explorer if you are using chrome or firefox.   If that doesn't work (because you also installed the IE flash update) use another computer at school or work or something that is really out of date for some reason (thats what I do)

Worse case scenario, you will just have to uninstall flash player, upload your image, then re-install flash player.

also see for a discussion of this already:  https://forums.elementalgame.com/338382