While reviewing first quarter sales transactions, an internal auditor discovered that 10 invoices for a...

While reviewing first quarter sales transactions, an internal auditor discovered that 10 invoices for a new customer had not been posted into the accounts receivable subsidiary ledger. Those 10 invoices were listed in an error report automatically generated by the sales processing system. The system had rejected the invoices because the customer's account number was not found in the customer master file. In this scenario, which of the following controls was lacking?