Extraordinary NCU &2 is not being processed

What causes this issue?

<DS:GLOS.49A0097A7B224424E10000000A421392>Net calculation unit</> (NCU)
&V1&, &V2&, valid for time interval &V3& is intended to be used for an
<DS:DE.PSSC_EXTRAORDINARY_NET_CALC>extraordinary net calculation</>.
Current processing of the net calculation also involves a regular NCU in
parallel. A settlement period should also be available for the
corresponding regular NCU. This settlement period could not be found due
to an internal error.

System Response

The system does not process the current NCU.

How to fix this error?

Contact your system administrator.

Procedure for System Administrators

Check if the problem has been caused by a customer-specific adjustment.
If this is not the case, contact SAP.

Error message extract from SAP system. Copyright SAP SE.