What is post type of Replies in Wordpress BBPress?

Question

I did count active in 7 days topics of my Wordpress page. But It counts only Active (replied) topics not actual replies- I need more dynamic number to lure people using forum.

function count_new_forum_posts() {

    $today = date("Y-m-d");

    $date2 = date("Y-m-d", strtotime($today . "-7 Day"));   
    $args = array(
            'post_type' => 'topic',
            'meta_query' => array(
                array(
                    'key' => '_bbp_last_active_time',
                    'value' => $date2,
                    'type' => 'DATE',
                    'compare' => '>='
                        ),
                    )
    );

    $posts_query = new WP_Query($args);
    $the_count = $posts_query->post_count;

    return $the_count;

    }

    add_filter('wp_nav_menu_items', 'new_forums_notice_to_menu', 10, 2);

     function new_forums_notice_to_menu($items, $args) {
         if(count_new_forum_posts() > 0){
              if( $args->theme_location == 'primary' )
              $items .= '<li><a href="http://***/forums/" text-transform="lowercase" text-shadow="2px 1px 2px black"><font color="red">Šios savaitės naujos žinutės forume: <span>'.count_new_forum_posts().'</span></font></a></li>';
         return $items;
     }else{
                   if( $args->theme_location == 'primary' )
              $items .= '<li><a href="http://***/forums/" text-transform="lowercase" text-shadow="2px 1px 2px black"><font color="gray">Šią savaitę forume dar niekas nepasisakė</span></font></a></li>';
         return $items;
     }
    }

When i try to change post_type to 'reply' or 'replies' It counts to 0.