When doing ajax calls within your custom plugins to custom server files, and in need of using WordPress functions, one might be attempted to call wp-load on the system. This is really bad practice as it loads the whole framework again.
Try this
add_action('wp_print_scripts','myscript'); function myscript() { } wp_enqueue_script('myscript','...myscript.js',...);
The bold parts need to matchup
add_action( ‘wp_ajax_myaf‘, ‘myaf‘ );
and is the function name
this is used when a user is not logged in
add_action( ‘wp_ajax_nopriv_myaf‘, ‘myaf‘ );