Comment Navigation

I want to replace the “older comments” and “newer comments” with something like,
“Page 1, 2, 3, …”

I installed the plugin wp-pagenavi, and followed the instruction to
change the code:

<div class="alignleft"><?php previous_comments_link() ?></div>
<div class="alignright"><?php next_comments_link() ?></div>

with the code,
<?php wp_pagenavi(); ?>

in comments.php.

But nothing happened.

Please help instruct how to do.

Thank you!