cron job does not work, why?

The interval of “debug60s” is 60 seconds.

if (!wp_next_scheduled('auto_update_sddl_event')) {
// only for debug
	$file = fopen("c:/1.txt", "a");
	fwrite($file, "0");
	fclose($file);
	wp_schedule_event(current_time('timestamp'), 'debug60s', 'auto_update_sddl_event');
}

function auto_update_sddl_func() {
// only for debug
	$file = fopen("c:/1.txt", "a");
	fwrite($file, "1");
	fclose($file);
}
add_action('auto_update_sddl_event', 'auto_update_sddl_func');

I wish auto_update_sddl_func would execute every 60 seconds. However, it’s never run, not even once. In the file “C:/1.txt” I can only find “0”.

I’ve read codex but still have no idea at all. Can you help me? Thanks a looot!