Not permitted to use only presorting keys with no subtotal

What causes this issue?

In all schema steps, you have only used presorting keys for which the
<ZH>No subtotal</> indicator is set. This is not permitted. Refer to
the documentation on <DS:DE.LINESORT>presorting keys</>.

System Response

The schema is inconsistent and cannot be saved.

How to fix this error?

Use appropriate presorting keys.

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