WordPress Navigation regarding >> and

I’m using the following code for my navigation in the single.php file,

<?php previous_post('&laquo; &laquo; %', '', 'yes'); ?>
| <?php next_post('% &raquo; &raquo; ', '', 'yes'); ?>

And the “»” are not showing up as links, but instead just text, unlike the example on https://codex.www.ads-software.com/Next_and_Previous_Links

Anyone know why that is?

Thank you