There are two places to create invoices -- either directly from the Booking or from the Sales Order.
If you create an invoice from the Booking, the line items will be containers. If you create from the Sales Order, then you should be simultaneously completing the sales order and the line items will reflect the sales order lines.
- Click the "Create Invoice" button from the Invoices tab.
- The invoice that appears has not been saved. Make appropriate changes and press Save.
- From the Reports Menu select either Bill or Commercial Invoice report.