Line balances can not be created for factory layouts of type &1

What causes this issue?

You have tried to create a line balance for a specific part of a line
structure. However, you can create line balances only for line
networks, lines, or groups of alternative lines.

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.