Can't figure out excluding categories on RSS

I’ve looked through the forum and found this code, which I input into my functions.php file to try to exclude a few categories from RSS. It’s not working though. Could there be a conflict between WordPress RSS feed and Feedburner? I run both and the Feedburner feed does exclude the categories because I’ve gone into their system and excluded them. But the original feed still shows everything. I can’t figure it out. Any ideas? thanks

I’m running a child theme and this is the complete content of that file:

<?php

function myFilter($query) {
if ($query->is_feed) {
$query->set(‘cat’,’-317, -1, -487, -691′);
}

return $query;
}

add_filter(‘pre_get_posts’,’myFilter’);

?>