PHP Header Location Doesn't work - Mobile Redirection Script in Wordpress

I found this code on various sits on the internet but i somehow can't bring it to work..

<?php
header("Location: http://ift.tt/1JP4AH7");
exit;
?>

I uploaded this code as test.php to 2 different hosts and both won't redirect. On the second host i edited the header.php file from Wordpress theme so there is no other Code displayed to the client before the Header happens.

1 Host: Returns nothing as result.

2 Host: 502 Bad Gateway The server returned an invalid or incomplete response.

Any ideas or suggestions would be highly appreciated!