Settlement date in incoming file is missing or not unique

What causes this issue?

All file records must have the same settlement date.
Reason: The amounts of all data records are added up and posted as a
collective invoice with the parameters and account assignments from the
main card. The collective invoice posting date is formed from the
settlement date, which is why it must be clear.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Divide data records having different settlement dates into separate
card files.

Error message extract from SAP system. Copyright SAP SE.