May,
Just a heads up, for many SAP Objects you need to pass in the elementsof. If not, you may run into errors related to "required element missing" even if you're trying to pass it later in the code.
For example, you may need to do it in this fashion:
var newSalesOrderRootElements : elementsof SalesOrder;
newSalesOrderElements.AccountID = "123";
var newSalesOrder = SalesOrder.Create(newSalesOrderRootElements);
The same may apply to Items:
var newSalesOrderItemElements : elementsof SalesOrder.Item;
newSalesOrderItemElements.ItemProduct.ProductKey.ProductID.content = "P100001";
newSalesOrderItemElements.FirstItemScheduleLine.Quantity = 1;
var newSalesOrderItem = newSalesOrder.Item.Create(newSalesOrderItemElements);