Add text to WooCommerce Customer processing order email after order table

I’m trying to add some text after the order table. My code is:

function print_help_links(){
 // Print some links.
 echo "Print some links";
}
add_action(' woocommerce_email_after_order_table','print_help_links');

It doesn’t work. What i am doing wrong? I know how to add through editing email template file, but i want to add with a hook.

Thanks.