addthis's script fails to load in Chrome

I ran into the same issue today. Try using https. It solved the problem for me.

https://s7.addthis.com/js/300/addthis_widget.js#pubid=ra-51aee1dc1b323034

AdBlock and other extensions block "addthis" http://support.getadblock.com/discussions/problems/26572-adblock-blocking-adthis-widget