Hi,
Do you have a system plugin which can modify your HTML content dynamically ?
Because there is an weird issue in your page, we can see the code
<span class="hikashop_social_google_right"><plusone size="standard" count="false"></plusone></span>
But, the social plugin is added the content using
return '<span class="'.$c.'"><g:plusone '.$size.' count="'.$count.'"></g:plusone></span>';
Which mean that "<g:plusone>" has been transformed into "<plusone>" but something else.
And because the tag name is not correct, the Google PlusOne javascript can't find the tag to replace.
Regards,