custom post types permalinks

Hi, I am trying to workout what i am doing wrong with the permalinks structure. I have created this page:

http://adamknight.com.au/AboriginalArtSpecialistAustralia/artists/

When I go to this page: http://adamknight.com.au/AboriginalArtSpecialistAustralia/artist/barbara-reid/ and select the
‘Artists’ link in the breadcrumbs the pages goes to this page http://adamknight.com.au/AboriginalArtSpecialistAustralia/artist

So I have 2 pages:
1.http://adamknight.com.au/AboriginalArtSpecialistAustralia/artist
2.http://adamknight.com.au/AboriginalArtSpecialistAustralia/artists

I like the http://adamknight.com.au/AboriginalArtSpecialistAustralia/artists as i have styled it

How do i fix permalinks in url and breadcrumb.

I have tried to change
'rewrite' => array( 'slug' => 'artist' ),

to

'rewrite' => array( 'slug' => 'artists' ),

but get error?

thanks Mike

function codex_custom_init() {
  $labels = array(
    'name'               => 'Artists',
    'singular_name'      => 'Artist',
    'add_new'            => 'Add New',
    'add_new_item'       => 'Add New Artist',
    'edit_item'          => 'Edit Artist',
    'new_item'           => 'New Artist',
    'all_items'          => 'All Artists',
    'view_item'          => 'View Artist',
    'search_items'       => 'Search Artists',
    'not_found'          => 'No artists found',
    'not_found_in_trash' => 'No artists found in Trash',
    'parent_item_colon'  => '',
    'menu_name'          => 'Artists'
  );

  $args = array(
    'labels'             => $labels,
    'public'             => true,
    'publicly_queryable' => true,
    'show_ui'            => true,
    'show_in_menu'       => true,
    'query_var'          => true,
    'rewrite'            => array( 'slug' => 'artist' ),
    'capability_type'    => 'post',
    'has_archive'        => true,
    'hierarchical'       => false,
    'menu_position'      => null,
    'menu_icon' => 'dashicons-art',
    'supports'           => array( 'title', 'editor', 'thumbnail', 'excerpt' )
  );

  register_post_type( 'artist', $args );
  flush_rewrite_rules();