A very basic phrase question

[essam.me]

Hello,

I'm coding my first hack so I'm trying to add a phrase and use it like this:
print_stop_message('my_phrase');
As recommended in the vBulletin manual I added it in Control Panel Home Pages and I selected my product.

So why the following code is giving me "Could not find phrase 'my_phrase'.":

<?php

$phrasegroups = array('cphome');
$specialtemplates = array();

require_once('./global.php');

print_cp_header('test');

print_stop_message('my_phrase');

print_cp_footer();

?>

Your help is greatly appreciated.