diff --git a/backend/app/plugins/wiaas/includes/class-wiaas-cart.php b/backend/app/plugins/wiaas/includes/class-wiaas-cart.php
index 69f4972..d057b15 100644
--- a/backend/app/plugins/wiaas/includes/class-wiaas-cart.php
+++ b/backend/app/plugins/wiaas/includes/class-wiaas-cart.php
@@ -448,7 +448,9 @@ class Wiaas_Cart {
 			'_wiaas_supplier_product_no',
 			'_wiaas_supplier_organization_id',
 			'_wiaas_product_price',
-			'_wiaas_earliest_installation_additional_days'
+			'_wiaas_earliest_installation_additional_days',
+			'wiaas_installation',
+			'wiaas_installation_date'
 		) );
 	}