problems with installation (not shortcode)

Hello, I am not a php/wordpress expert, so please sorry for the question which looks like an easy task to fix. I added the following code before the loop of single.php file: if( function_exists('dot_irecommendthis') ) dot_irecommendthis(); Then, just below the loop inizialization: $no_likes = '<span class="post-stats-label">' . Likes . '</span><i class="fa fa-heart"></i> <span>' . dot_irecommendthis() . '</span>'; $no_likes is finally added in the position where I want it should be. No values are registered. Could you help me? What is wrong on that? FYI: I have also tried the original code reported in the plugin homepage: <?php if( function_exists('dot_irecommendthis') ) dot_irecommendthis(); ?> but it does not work. Thank you.