[Plugin: Socialize] Inline Stumble button won't show on first post

I have several buttons inline and at the bottom.
The other buttons (fb, twitter, g+) show up fine. But stumbleupon will only show up inline on older posts, not the newest one.
Any suggestions??

Client website is: http://www.motherhoodinnyc.com/

http://wordpress.org/extend/plugins/socialize/