Unable to determine a calculation schema

What causes this issue?

The calculation schema is needed to determine the <GL:net_price>net
price</>/<GL:effective_price>effective price</>.

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?

Check your input.
INCLUDE NA_SYSADMIN LANGUAGE EN
The latter can make the necessary settings using the Implementation
Guide (IMG): <DS:SIMG.SIMG_CFMENUOLMEOMER5>Define calculation schema</>

Error message extract from SAP system. Copyright SAP SE.