You have unprocessed records in the staging table from an earlier import. To overwrite the unprocessed records, click OK. ...

You have unprocessed records in the staging table from an earlier import. To overwrite the unprocessed records, click OK. If you don't want to overwrite them, click Cancel, click the Navigation list, and go to Accounts Payable > Periodic > One-time vendors > Process one-time vendors and generate invoices.