“Previous Posts” Navigation

I have several WordPress sites, and this is the first time I’ve run into this particular issue. The site where I’m testing a new theme is here, and the “Previous Briefs” and “Most Recent Briefs” navigation isn’t working. When I click it, it’s going to the same post, not the next post. It’s the same code I’m using on other sites, so I’m not sure what’s wrong. Here’s the code:

<div class=”navigation”><center><?php posts_nav_link(”,”,'<–Previous Briefs’) ?>      |      <?php posts_nav_link(”,’Most Recent Briefs–>’,”) ?></center></div>

Any ideas? I appreciate your help!!!