Make sure your Front Page ratings are enabled for excerpts. In addition, your theme’s front page template must use the_excerpt() or the_content() methods to show/load the excerpts. We use this method’s hook to add the rating code. You can either try to fix that, or you can add our PHP shortcodes directly to your theme’s front page template.

Don’t panic – you are not alone! Your custom theme’s developer forgot to call wp_footer()in the footer template file (usually named footer.php). Our star ratings core JavasSript is loaded on this action hook. Once this fixed the ratings should appear.

More info here - http://codex.wordpress.org/Theme_Development#Plugin_API_Hooks

First, make sure you’ve enabled the ratings for comments in your admin’s dashboard. Once you sure it’s enabled, but still doesn’t work, a common cause can be that your theme isn’t using comment_text() to display the comments text. A common mistake by theme developers is the use of get_comment_text() instead of comment_text(). Try to switch between those and it should fix the issue. If you are awesome, contact the theme developer and let him know about the issue so he can fix it for everyone else.

Check out if you have any active caching plugins in your WordPress, they might cause this affect. In addition, we use local caching which is updated for every 5 minutes to increase the plugin performance.