Unable to change checkout placeholder text

I needed to change the default fields, but there was a small mistake in my code. The correct code was:

add_filter( 'woocommerce_default_address_fields', 'uwc_new_address_one_placeholder', 1 );

   function uwc_new_address_one_placeholder( $address_fields) {
       $address_fields['address_1']['placeholder'] = 'Address line 1';
       $address_fields['address_2']['placeholder'] = 'Address line 2';
       return $address_fields;
       }   

Notice the change to $address_fields on line 3