Highend Error Code: Non-numeric value encountered

Hi
The following warning is displayed on my website:

Warning: A non-numeric value encountered in /home2/monforde/stompukulele.com/wp-content/themes/HighendWP/functions/theme-likes.php on line 55.

The page where the warning is displayed is:

http://stompukulele.com/uke-news/

As far as I can tell, I have the latest version of HighEnd.

Any help you can offer would be greatly appreciated.

Thanks

Katy