widget doesn't dispaly any thing

hi,

the plugin is counting views in good way. but the widget doesn’t display any thing with all options?

i tied to use below query but still not showing any thing >>

<?php if (function_exists('get_most_viewed')): ?>
    <ul>
        <?php get_most_viewed('post', 5); ?>
    </ul>
<?php endif; ?>

did i miss any thing?

https://wordpress.org/plugins/wp-postviews/