I'm doing my first totally custom Drupal 7 theme. I have the page.tpl.php file working fine and have header and footer regions working, until I move this:
<?php print render($page['main_menu']); ?>
into region--header.tpl.php - the menu is no longer generated - the html around the PHP is generated - nav etc. so I know drupal's reading the template file OK.
The same code works fine if it is in page.tpl.php
Any help greatly appreciated.