skip cart

Hi i’m using a code in functions.php to skip the cart. It works fine with normal products i create, but it doesn’t work with the donation product this plugin creates automatically. Which would be the reason?
This is the code:

//Esquivar carrito e ir directo al checkout
add_filter( ‘woocommerce_add_to_cart_redirect’, ‘skip_woo_cart’ );

function skip_woo_cart() {
return wc_get_checkout_url();
}