Custom tags, custom posts and 404 issue

Hi

I am struggling to add custom tags to custom page (portfolio). I want tags called resource tags to help navigate or find certain posts that contain links to resource files I have uploaded. Eg a tag ‘Code of practice’ will bring up all resources about code of practice.

I have added the code:

// Set up resource tags

function resourcetags_init() {
	// create a new taxonomy
	register_taxonomy(
		'tags',
		'portfolio',
		array(
			'label' => __( 'Resource Tags' ),
			'rewrite' => array( 'slug' => 'resourcetags' ),

		)
	);
}
add_action( 'init', 'resourcetags_init' );

I have then added:

<?php the_terms( $post->ID, 'resourcetags', 'Resource tags: ', ', ', ' ' ); ?>

to the single-portfolio.php file to call the tags into the page.

All of the above works apart from when I click on the tags in the page and I get a 404 error.

I have tried using the code above and plug-ins to manage it for me and I get the same issue. Does anyone have any ideas?