this code is not displaying any thing when i run.

<?php

$offset = 0;

$find = 'Pak';
$string_lenght = strlen($find);

$string = 'Pak Pak Pakistan her dil azam hamara Pak Pak is tan';


while ($string_possition = strpos ($string, $find, $offset)){

echo $find. 'find at: '.$string_possition. '<br>';
$offset = $string_possition + $string_lenght;
}


?>