Invoking a callback to display metaboxes

I am customising a post type:

add_action( 'init', 'register_team_sheet' );
function register_team_sheet(){
  $labels = array(...);
  $args = array(...);
  register_post_type( 'team_list_event', $args );
}

I have defined my metaboxes

function team_list_add_meta_box(){
  add_meta_box('team_list_event','Team Event fields','team_event_show_box', 'post');
}
add_action('admin_menu','team_list_add_meta_box');

And defined my callback:

function team_event_show_box(){
  echo '<input type="hidden" name="team_list_meta_box_nonce" value="', wp_create_nonce(basename(__FILE__)), '" />';
  $box_fields=array(...);
  foreach($box_fields as $field){
  ... render field...
}

But my callback never gets called and the metaboxes are never rendered.

This is understandable because I haven’t linked the register_team_sheet() function to the callback.

The register_team_sheet function is visible in the Dashboard and can be invoked, but the metabox fields are not drawn.

How do I go about making sure that the callback is called when the register_team_sheet post type is selected?

Many thanks,

Dave