Settlement amount has an incorrect +/- sign

What causes this issue?

You want to settle an amount &V1& using an amount settlement rule,
which has a different +/- sign than the original amount &V2& ( &V3& ),
and is not allowed.

System Response

The system does not allow settlement.

How to fix this error?

Check your settlement rules.

Error message extract from SAP system. Copyright SAP SE.