Since you responded that the url is your site, I would guess that the include and requires are for your own site, it would appear that you are pointing to the files in a non-standard way.
By routing through a url, you would require Joomla to set up for every file. Normally, you would just point to the exact file:
include(JPATH_COMPONENT . '/views/view_name/tpl/default.php');
You can look here for the different path constants that Joomla makes available.