Show # of comments on Single Post page

Hello,

I would like to show the number of comments a post has beneath the full post in the Single Post page. I have inserted the following code into the Single Post file:

<?php comments_popup_link('Comment »', '1 Comment »', '% Comments »'); ?>

But it doesn’t seem to be working. Is there some other call I have to insert into this document to make it work?

Thank you!

-ben