Call error in function module 'RULES_DETERMINE'

What causes this issue?

The interface 'I_AFATYP' was given the value &V1&.
However, this value is not valid.
You will find valid values in the documentation for the function
module.

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?

This is a program error.

Error message extract from SAP system. Copyright SAP SE.