Same as the post titled "HACK for displaying post in WP pages wif MORE TAG working." By default, WP has removed the comments display in their page system.
To enable it, just add this before the comment_link_popup function,
<?php $wp_query->is_page = '0'; ?>
The result will be...
<?php $wp_query->is_page = '0'; comments_popup_link('No Comments »', '1 Comment »', '% Comments »');?>
Drop me an email if you find the hack is useful. My email is mickeyckm [at] gmail [dot] com.