How To GEO IP Location Redirect Wordpress

I have placed the below code in my themes header.php file in the head tag
Unfortunately, no redirects have taken place
I am using cloud flare to generate the HTTP IP.
I have Wordpress multisite w/ subdomains configured running twenty sixteen theme:

What i am doing wrong?
I am in australia:

<?php $user_country_code = strtolower($_SERVER["HTTP_CF_IPCOUNTRY"]);
if($user_country_code=="au") {
header( 'Location: http://'.$user_country_code.'.vividcollege.com');
} else {
header( 'Location: http://example.com');
}

?>