Displaying custom taxonomy in the admin list of a custom post type

I’m trying to list the terms of a custom taxonomy (‘genre’) in the overview table in the admin area for a custom post type (‘station’). To get this, I tried the following code in my theme’s functions.php file:

register_taxonomy('genre', 'station', array(
    'labels' => array(
        'name' => _x('Genres', 'taxonomy general name', 'loudfm_theme'),
        'singular_name' => _x('Genre', 'taxonomy singular name', 'loudfm_theme'),
        'search_items' => __('Search Genres', 'loudfm_theme'),
        'popular_items' => __('Popular Genres', 'loudfm_theme'),
        'all_items' => __('All Genres', 'loudfm_theme'),
        'parent_item' => __('Parent Genre', 'loudfm_theme'),
        'parent_item_colon' => __('Parent Genre:', 'loudfm_theme'),
        'edit_item' => __('Edit Genre', 'loudfm_theme'),
        'update_item' => __('Update Genre', 'loudfm_theme'),
        'add_new_item' => __('Add New Genre', 'loudfm_theme'),
        'new_item_name' => __('New Genre Name', 'loudfm_theme')
    ),
    'hierarchical' => true
));
add_filter('manage_station_posts_columns', 'station_edit_columns');
add_action('manage_posts_custom_column',  'station_custom_columns');
function station_edit_columns($columns){
    $columns = array(
        'cb' => '<input type="checkbox"/>',
        'title' => __('Station Title', 'loudfm_theme'),
        'description' => __('Description', 'loudfm_theme'),
        'genre' => __('Genre', 'loudfm_theme')
    );
    return $columns;
}
function station_custom_columns($column){
    global $post;
    switch ($column) {
        case 'description':
            the_excerpt();
            break;
        case 'genre':
            $genre = get_terms(array(
                'taxonomy' => 'genre',
                'include' => get_post_meta($post->ID, 'maingenre', true)
            ));
            echo '<a href="' . get_term_link($genre[0]) . '" title="' . sprintf(__('View all stations with the genre %s', 'loudfm_theme'), $genre[0]->name) . '">' . $genre[0]->name . '</a>';
    }
}

In my case I don’t simply want to list all selected genres of a station, but only the main genre whose id is stored in the field ‘maingenre’ of the custom post type. That’s why I’m using the get_terms function with the ‘include’ parameter. But sorrily I get an ‘Invalid taxonomy’ error back (as WP_Error object). Using get_the_term_list works without errors, but with this function I am not able to display only the main genre.

Can anyone tell me, why get_terms is not working here and how I can get it to work? Thank you!