save order prestashop web service - web-services

Question

I'm newbie with prestashop webservice, I'm trying to save orders in prestashop
database but i'm getting this error : table ps_orders doesn't exist, which is normal because prefix of my tables is different than ps_ :
here is my code :
define('DEBUG', true);
define('PS_SHOP_PATH', 'http://localhost/prestashop');
define('PS_WS_AUTH_KEY', 'CQP84L4R3GB6IV99E5WSP4JPSWXDYE1R');
require_once('./PSWebServiceLibrary.php');
try{
$webService = new PrestaShopWebservice(PS_SHOP_PATH, PS_WS_AUTH_KEY, DEBUG);
$xml = $webService->get( array('url' => PS_SHOP_PATH.'/api/carts?schema=blank') );
$resources = $xml->children()->children();
$id_currency = 3;
$id_lang = 2;
$id_product = 2571;
// $attribute_product =
$id_address = 8;
$qte_product = 1;
$id_customer = 3;
$id_carrier = 3;
$date_now = date('Y-m-d H:i:s');
$name_product = 'produit 111 ';
// $reference_product = ;
$price_product = 320;
$tax_inclu_product = 320;
$tax_excl_product = 320;
$order_module = 'cashondelivery';
$order_payment = 'Cash on delivery (COD)';
$total_paid = 355;
$total_paid_real = 355;
$total_products = $price_product;
$total_products_wt = $price_product;
$id_status = 5; // status de la commande : livré, en cours
$total_discounts =0;
$total_discounts_tax_incl = $total_discounts;
$total_discounts_tax_excl = $total_discounts;
$total_paid_tax_incl = 355;
$total_paid_tax_excl = 355;
$total_shipping = 35 ; //frais selon la ville de livraison
$total_shipping_tax_incl = $total_shipping;
$total_shipping_tax_excl = $total_shipping;
$xml->cart->id_currency = $id_currency;
$xml->cart->id_lang = $id_lang;
$xml->cart->associations->cart_rows->cart_row[0]->id_product = $id_product;
// $xml->cart->associations->cart_rows->cart_row[0]->id_product_attribute = $attribute_product;
$xml->cart->associations->cart_rows->cart_row[0]->id_address_delivery = $id_address;
$xml->cart->associations->cart_rows->cart_row[0]->quantity = $qte_product;
// Others
$xml->cart->id_address_delivery = $id_address;
$xml->cart->id_address_invoice = $id_address;
$xml->cart->id_customer = $id_customer;
$xml->cart->id_carrier = $id_carrier;
$xml->cart->date_add = $date_now;
$xml->cart->date_upd = $date_now;
// Adding the new customer's cart
$opt = array( 'resource' => 'carts' );
$opt['postXml'] = $xml->asXML();
$xml = $webService->add( $opt );
$id_cart = $xml->cart->id;
// ORDER
$xml = $webService->get(array('url' => PS_SHOP_PATH .'/api/orders/?schema=blank'));
// Adding dinamic and required fields
// Required
$xml->order->id_address_delivery = $id_address; // Customer address
$xml->order->id_address_invoice = $id_address;
$xml->order->id_cart = $id_cart;
$xml->order->id_currency = $id_currency;
$xml->order->id_lang = $id_lang;
$xml->order->id_customer = $id_customer;
$xml->order->id_carrier = $id_carrier;
$xml->order->module = $order_module;
$xml->order->payment = $order_payment;
$xml->order->total_paid = $total_paid;
$xml->order->total_paid_real = $total_paid_real;
$xml->order->total_products = $total_products;
$xml->order->total_products_wt = $total_products_wt;
$xml->order->conversion_rate = 1;
// Others
$xml->order->valid = 1;
$xml->order->current_state = 1;
$xml->order->total_discounts = $total_discounts;
$xml->order->total_discounts_tax_incl = $total_discounts_tax_incl;
$xml->order->total_discounts_tax_excl = $total_discounts_tax_excl;
$xml->order->total_paid_tax_incl = $total_paid_tax_incl;
$xml->order->total_paid_tax_excl = $total_paid_tax_excl;
$xml->order->total_shipping = $total_shipping;
$xml->order->total_shipping_tax_incl = $total_shipping_tax_incl;
$xml->order->total_shipping_tax_excl = $total_shipping_tax_excl;
// Order Row. Required
$xml->order->associations->order_rows->order_row[0]->product_id = $id_product;
//$xml->order->associations->order_rows->order_row[0]->product_attribute_id = $attribute_product;
$xml->order->associations->order_rows->order_row[0]->product_quantity = $qte_product;
// Order Row. Others
$xml->order->associations->order_rows->order_row[0]->product_name = $name_product;
// $xml->order->associations->order_rows->order_row[0]->product_reference = $reference_produc;
$xml->order->associations->order_rows->order_row[0]->product_price = $price_product;
$xml->order->associations->order_rows->order_row[0]->unit_price_tax_incl = $tax_inclu_product;
$xml->order->associations->order_rows->order_row[0]->unit_price_tax_excl = $tax_excl_product;
// Creating the order
$opt = array( 'resource' => 'orders' );
$opt['postXml'] = $xml->asXML();
$xml = $webService->add( $opt );
$id_order = $xml->order->id;
echo "Customer 1 : ".$id_customer." address: ".$id_address." cart: ".$id_cart." Order: .".$id_order;
} catch (PrestaShopWebserviceException $e) {
// Here we are dealing with errors
$trace = $e->getTrace();
if ($trace[0]['args'][0] == 404) echo 'Bad ID';
else if ($trace[0]['args'][0] == 401) echo 'Bad auth key';
else echo 'Other error<br />'.$e->getMessage();
}