Single.php conditional arguement

<?php
    $post = $wp_query->post;
    if ( post_type_exists( 'swc_staff' ) ) {
    include(TEMPLATEPATH . '/post-staff.php');

    } else {
    include(TEMPLATEPATH . '/post-news.php');
    }
    ?>

I am trying to split off my single.php so I have a different template for custom post type posts to news posts. Is this arguement correct? it doesnt work for me. Instead it shows post-staff.php for both custom posts read more AND regular posts read more permalinks.