sfc_like_button works on all pages/posts except one!

Have installed the plugin. It works great except for the sfc_like_button on https://bhbeat.com/vouchers.

The button renders, but when you click the Like count goes up to 1 and then back to 0. The widget appears on other posts and pages and works, so the code should be OK. I am using the following code in the Advanced Text Widget.

<div style="width: 55px; height: 75px; padding: 0px 0 0 0; position: relative; top: -5px; float: left;">
<?php if (function_exists('sfc_like_button')) echo sfc_like_button(array('layout'=>'box_count'));?>
</div>

Any insight into why this one page doesn’t work is greatly appreciated.