Alright. I found the problem. In my get_labels.php, I was <?php include 'afile.php' ?>. This ahad to change to ../afile.php
So now "includes/get_labels.php?json=true&" is working. Now comes the real problem. I need this to work in a template I'm making in Wordpress. So far, it looks lke the main script isn't triggering. It is loading, because I can test this with "alert('test');".