Make an entry in the "Line ID costs" field in the valuation method

What causes this issue?

You have not made an entry in the <LS>Line ID costs</> field in the
Expert Mode, although you are using
<DS:GLOS.cost_planning>structure-oriented planning</> for an
<DS:GLOS.internal_order>internal order</> or
<DS:GLOS.project>project</>.
In structure-oriented planning, you enter estimated values for each
period. Because these values are not assigned to any cost element, they
cannot be automatically assigned to a <GL:line_ID>line ID</>.
The field <LS>Line ID costs</> enables you to manually assign the
estimated values to a line ID.

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?

Go into the Expert Mode of the valuation method and make an entry in
the field <LS>Line ID costs</>.

Error message extract from SAP system. Copyright SAP SE.