update_post_meta for anonymous_name field not working (3.0.5)

// Update Custom Meta.
 if ( ! empty( $args['anonymous_name'] ) ) {
 update_post_meta( $post_id, 'anonymous_name', $args['anonymous_name'] );
 }

field for guest (name) is always empty, despite entering that name. Therefore, there is no meta data saved into database, and user display name is always “Anonymous”.