problem with maxlength html attribute

Hi,
Woocommerce 2.6.7
WooCommerce Checkout Manager: 4.0.9

The probleme: to handle maxlength attribut for a textzone (for example shipping.address_1) i add this code in my function.php in my child theme:

`add_filter( ‘woocommerce_shipping_fields’ , ‘aliant_controle_shipping_zones’ );

function aliant_controle_shipping_zones( $fields ) {
$fields[‘shipping_address_1’][‘maxlength’] = ’30’;
return $fields;
}`
If i disable WooCommerce Checkout Manager, this code works fine.
If i enable WooCommerce Checkout Manager, i have “maxlength = 0” in the final html page.