Order &: Function not possible for collective orders

What causes this issue?

This BAPI method does not process individual orders. It only
processes entire order networks. Therefore, it does
not accept any dependent orders but only the leading order of an order
network.

System Response

If dependent orders of an order notwork are transferred to this
BAPI method, they are not processed unless the leading order of the
corresponding order network has also been transferred.

How to fix this error?

If you want to process orders of an order network using this method,
transfer the leading order of the order network to the
BAPI method.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.