[Plugin Recent Comments] Not working right

So i currently just put in the recent comments in a side bar and it comes up fine but it doesnt display the recent comments, kinda of random ones.

here the code

<?php if (function_exists('get_recent_comments')) { ?>
   <h2><?php _e('Recent Comments:'); ?></h2>

<ul><?php get_recent_comments(); ?></ul>
<?php } ?>