Plugin Menus and submenus

Hi

I’m writing a plugin that requires a few subpages.
I have my initial defined like this:

add_action('admin_menu', 'acme_menu');

function acme_menu() {
	add_menu_page('Acme', 'Acme', 'manage_options', 'acme', 'acme_events');
}

This works fine and I display the content with acme_events.

Now I’m trying to create a sub-menu like this

function acme_sub_menu() {
	add_submenu_page('acme', 'Import Acme Event', 'Import Acme Event', 'manage_options', 'import-event', 'import_event');
}

The menu appears, but the slug is wrong – it shows ‘wp-admin/import-event’ instead of ‘?page=import-event’ – clicking it gives me a frontend 404.

What am I doing wrong?

I hope someone can help me as I have not had much luck with these forums. I’ve posted numerous equally urgent questions that remain
unanswered. Are there any OTHER wordpress forums?