The customs office is not valid for the transportation point country

What causes this issue?

You have tried to enter a customs office which has not been defined for
the country assigned to this point.

System Response

The system doesn't accept the entry.

How to fix this error?

Enter a permitted customs office (use F4 help) or leave the 'Customs
office' field blank.

Error message extract from SAP system. Copyright SAP SE.