&: Maintain default combination for from_country & - & to_country &

What causes this issue?

The entry you made for conversion is not unique for the &V1& from
country &V2& - &V3& to country &V4&.
The reason for this is that an entry is already maintained for the &V1&
from country &V2& - &V3& to country &V4&.
If you want to have the system to be able to execute the conversion
automatically, you must maintain the flag "Default combination" for an
entry and then inform the system that this entry is to be used - should
several possible entries exist.

System Response

The system issues a warning message.

How to fix this error?

Maintain the flag 'Default combination' for a combination.

Error message extract from SAP system. Copyright SAP SE.