If you have booked something with a supplier that doesn't have a code, rather than 'Direct Supplier', please create a new code.
This is so we have more accurate data to report on (and hit suppliers up for deals and discounts etc)
To do this, click on Suppliers on the left hand side of VTO and then Add New
Choose a code for the Supplier, enter the Supplier's Name, choose 'On Invoice' under General, and then click Create New (no need to enter anything else)
You can then use the supplier code in your trip.