Number of Facebook comments

We have used the following code to display comments for articles on the Wordpress site. For some reason, the count goes back to zero today, even if the page has a permalink to multiple comments.

<fb:comments-count href=".get_permalink()."></fb:comments-count>

      

        
        
        
      

    

Has anyone else had problems with Facebook comments recently?

We tried hardcoding href = "http://example.com/" as shown here with no luck.