Assign all costs of cost element & to line ID of category K

What causes this issue?

You can calculate <DS:GLOS.work_in_process>work in process</> for
<DS:GLOS.product_cost_collector>product cost collectors</> if the
product cost collector has a <DS:GLOS.results_analysis_key>results
analysis key</> with results analysis type <ZH>S</>
(<DS:GLOS.WIP_calculation>WIP calculation</> using
<DS:GLOS.target_costs>target costs</>).
To calculate work in process by period, the system valuates the
<DS:GLOS.WIP_quantity>WIP quantities</> confirmed at the reporting
points with the standard costs of the operation.
In your case, the system cannot valuate the work in process because
there are cost elements under which actual costs have been written that
are either not assigned to any line IDs or that are assigned to a line
ID that is not category <ZH>K</>. The line IDs under which the costs
are updated must be assigned to <DS:DE.KATEGORIE>category</> <ZH>K</>
(costs).

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 Customizing and check the following:
The assignment of the cost elements to line IDs
The categories of the line IDs (in the Update)

Error message extract from SAP system. Copyright SAP SE.