Meta box doesn't appear

This was working before. I was able to see the meta box fields in my dashboard. (I couldn’t save meta field data, but that’s another topic.)

Now I can’t even get the meta data to appear. I can see the Concerts post type, and the Add New button, but I don’t see the fields. I’m probably missing something obvious. Again, there’s no ‘save’ code but the meta box fields should be showing up.

Here’s my code:

// Register our new custom post type CONCERT
function register_concert_type() {
	register_post_type( 'concerts',
		array(
			'label' => 'Concerts',
			'labels' => array(
				'name'=>'Concerts',
				'singular_name'=>'Concert'),
			'public' => true,
			'menu_position' => 5,
			'supports' => array( 'title')
		)
	);
}
add_action( 'init', 'register_concert_type' );

// ADD "CONCERT" META BOX:
function add_concert_meta() {
	add_meta_box(
		"concert_details_meta",
		"Concert Details",
		"concert_details",
		"concert"
	);
}
add_action('admin_init', 'add_concert_meta');
//add_action('add_meta_boxes', 'add_concert_meta' );

// Add custom fields:
function concert_details(){
	global $post; // Is this needed?
	//wp_nonce_field( plugin_basename( __FILE__ ), 'concert_details_nonce' );
	$concert = get_post_custom($post->ID);
	$date = $concert["date"][0];
	?>Concert Date: <input name="date" id="date" value="<?php echo htmlspecialchars($date); ?>" ><br>
	<?php
}