WordPress Custom role with custom cababilities can’t access the dashboard

I’m writing a plugin which creates a new post_type and a corresponding role which can only add/edit/etc the new post_type. Everything works as expected, but the user assigned my custom role cannot view the dashboard. Once the user logs in, they immediately get the following error:

“You do not have sufficient permissions to access this page.”

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However, the login is successful, and the “edit” links appear on the custom posts when the user browses the site. This user can even edit/add new custom posts via the toolbar, but as soon as he/she clicks “Dashboard” or any other link not directly linked to the custom post_type they get the above error message.

I think this means my custom capabilities are working… but TOO well (as in too strictly). I’d like to also permit the basic “subscriber” permissions along with the capabilities I defined for the custom post_type. I’ve read and re-read the codex about capabilities & roles and it appears that I should be able to do what I want by adding 'read' => true to my array of capabilities, but it doesn’t seem to be working. Here’s my code:

add_action('init', 'setup_dictionary_post');

//Register custom post type 
function setup_dictionary_post() {

$capabilities = array(
    'publish_posts' => 'publish_dictionary_entry',
    'edit_posts' => 'edit_dictionary_entry',
    'edit_others_posts' => 'edit_others_dictionary_entry',
    'delete_posts' => 'delete_dictionary_entry',
    'delete_others_posts' => 'delete_others_dictionary_entry',
    'read_private_posts' => 'read_private_dictionary_entry',
    'edit_post' => 'edit_dictionary_entry',
    'delete_post' => 'delete_dictionary_entry',
    'read_post' => 'read_dictionary_entry'
);

$labels = array(
    'name' => 'Dictionary Entries',
      'singular_name' => 'Dictionary Entry',
      'menu_name' => 'Dictionary Entries',
      'add_new' => 'Add New',
      'add_new_item' => 'Add New Dictionary Entry',
      'edit' => 'Edit entry',
      'edit_item' => 'Edit Dictionary Entry',
      'new_item' => 'New Dictionary Entry',
      'view' => 'View Dictionary Entry',
      'view_item' => 'View Dictionary Entry',
      'search_items' => 'Search Dictionary Entries',
      'not_found' => 'No Dictionary Entries Found',
      'not_found_in_trash' => 'No Dictionary Entries Found in Trash',
      'parent' => 'Parent Dictionary Entry',);

    register_post_type('dictionary_entry', array(
        'label' => 'Dictionary Entries',
        'description' => '',
        'public' => true,
        'show_ui' => true,
        'show_in_menu' => true,
        'capability_type' => 'dictionary_entry', 
        'capabilities'=>$capabilities, 
        'hierarchical' => false,
        'rewrite' => array('slug' => ''),
        'query_var' => true,
        'supports' =>     array('title','comments','revisions','thumbnail','author','page-attributes',),
        'labels' => $labels,
        )
    );

    flush_rewrite_rules(false);

    /********************** CUSTOM ROLE *****************************/
    add_role('dictionary_entry_author', 'Dictionary Helper', array(
        'publish_dictionary_entry' => true,
        'edit_dictionary_entry' => true,
        'edit_others_dictionary_entry' => true,
        'delete_dictionary_entry' => true,
        'delete_others_dictionary_entry' => true,
        'read_private_dictionary_entry' => true,
        'edit_dictionary_entry' => true,
        'delete_dictionary_entry' => true,
        'read_dictionary_entry' => true,
        // more standard capabilities here
'read' => true,
    ));

//I do some other stuff later in this function that isn't important.
//For example, I define a custom taxonomy for the new post_type...
}

I’m not sure why the 'read'=>true, isn’t accomplishing what I want. I’ve read several tutorials, and received some code from in which “meta capabilities” get mapped, but I’m not using it in my code because I don’t understand how it works and it doesn’t seem to be necessary. I could be wrong.