If you're shown that the export contains errors, you can view all errors under Settings → Shop → Pickware Import/Export Module in the detail view of the respective export.
To have the orders included in the next export, it's usually enough to check the individual line items and add additional accounts in the configuration for the respective business transaction.
Going forward, our DATEV module will also make it possible to create multiple exports for the same business transactions within a given period, so that the documents will be included in the next export after the configuration has been adjusted.