Why this add_filter doesn't work?

I want to add cancel button on my account, next to my ‘on-hold’ status orders

I use:

add_filter ('woocommerce_valid_order_statuses_for_cancel', 'my_valid_order_status');
function my_valid_order_status($a){
$a=array('pending','failed','on-hold');
return $a;
}

but no vail

I use:
add_filter ('woocommerce_valid_order_statuses_for_cancel', array('pending','failed','on-hold'))

not working either.

Anyone can help?

https://www.ads-software.com/plugins/woocommerce/