The sales area could not be determined.

What causes this issue?

No sales area could be determined for the order type and customer
selected.

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?

Possible solutions:
Enter a customer who is defined in a sales area that is also allowed for
the selected order type.
Select an order type in the initial screen that is allowed for the
customer's permitted sales areas.
Check whether more than one sales area exists for the combination you
entered. The sales area must be unique.

Error message extract from SAP system. Copyright SAP SE.