This message is encountered when:
1. Sales Order is billed via Transactions> Sales> Bill Sales Order.
2. Customer record have both:
- Term assigned in the Financial > Terms field.
- Credit Card number assigned under Financial > Credit Cards and Default Credit Card = T
3. Before saving the sales order the Credit Card numbers were removed under the Billing > Payment > Credit Card # field.
The transaction that will be created in this scenario would be a cash sale even if Credit Card information is complete. Payment Method takes precedent over terms.
Completely remove the value in the Payment Method field in sales orders to avoid encountering this error during billing.