Pool & not defined in & &

What causes this issue?

Your combination of valuation level and pool is not defined.

How to fix this error?

Please correct your input values. If this does not help, check whether
the entries in Customizing (table TPOOL are) correct.

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

Error message extract from SAP system. Copyright SAP SE.