Invalid Taxonomy

So I registered a custom post type as well as a taxonomy for that post type. I then created a couple items in that taxonomy, but when I go to click on any of them it turns up as Invalid taxonomy.

https://i42.tinypic.com/ncffi1.jpg

Here is the code I use to create my custom post type + taxonomy. I have it in a plugin.

<?php

/*
Plugin Name: Guides Post Type
Description: Guides Post Type
*/

class GW_Guides_Post_Type {
	public function __construct() {
		$this->register_post_type();
		$this->metaboxes();
		$this->guides_taxonomy();
	}

	public function guides_taxonomy() {
		register_taxonomy(
			'Guide Categories',
			'gw_guides',
			array(
				'hierarchical' => true,
				'label' => 'Guide Categories')
		);
	}

	public function register_post_type() {
		$args = array(
			'labels' => array(
				'name' => 'Guides',
				'singular_name' => 'Guide',
				'add_new' => 'Add New Guide',
				'add_new_item' => 'Add New Guide',
				'edit_item' => 'Edit Item',
				'new_item' => 'Add New Item',
				'view_item' => 'View News',
				'search_items' => 'Search Guides',
				'not_found' => 'No Guides Found',
				'not_found_in_trash' => 'No Guides Found In Trash'
			),
			'query_var' => 'guides',
			'rewrite' => array(
				'slug' => 'guides',
			),
			'public' => true,
			'menu_position' => 5,
			'menu_icon' => admin_url() . 'images/media-button-other.gif',
			'supports' => array( 'title', 'editor', 'excerpt', 'thumbnail' ),
			'has_archive' => true
		);
		register_post_type('gw_guides', $args);
	}	

	public function metaboxes() {
		add_action('add_meta_boxes','add_guides_meta');

		function add_guides_meta() {
			// css id, title, cb funct, page, priority, cb funct arguments
			add_meta_box('gw_guides_meta', 'Featured', 'guides_meta', 'gw_guides');
		}

		function guides_meta($post) {
			$featured = get_post_meta($post->ID, 'featured', true);
			?>
				<p>
					<label for="featured">Featured:</label>
					<?php
						if ($featured == "True") {
							$checked = 'checked';
						} else {
							$checked = '';
						}
					?>
					<input type="checkbox" name="featured" id="featured" value="True" <?php print($checked) ?> />
					<?php echo $featured; ?>
				</p>
			<?php
		}

		add_action('save_post', 'save_guides_meta');

		function save_guides_meta($id) {
			update_post_meta(
				$id,
				'featured',
				strip_tags($_POST['featured'])
			);
		}
	}

}

function add_gw_guides() {
	new GW_Guides_Post_Type();
}

add_action('init', 'add_gw_guides');