Enter the table to be used for conversion

What causes this issue?

You want to create a rule for the conversion of values. However, you
have not specified the table from which the values are to be converted.

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?

Please enter the name of the table to be used for converting the value.

Error message extract from SAP system. Copyright SAP SE.