I've just installed this plugin on a test version of a site - I didn't create the site, just doing some updates.
The site is running WP 3.7.1.
The problem I am having is that the buttons only show on some pages/posts sometimes. I've checked in Firefox 25.0.1, Chrome 31, Opera 18, IE8, Safari 5.1.7.
In most of the browsers above I have to refresh once or twice before the buttons show, then If I keep refreshing the page sometimes they will show and sometimes not.
There are quite a few plugins installed on this site, so could that be an issue?