Register action

Hello,

I am trying to register an action for my plugin, but it not working.

$base = elgg_get_site_url() . 'mod/better_settings/actions/header.php'; elgg_register_action("better_settings/header", $base, 'admin');

And my action is stored at...

mod/better_settings/actions/header.php

What am I doing wrong?
I made sure that there is content in header.php. It is just a word.