Cumulative received quantity is missing and is automatically determined

What causes this issue?

A cumulative received quantity has not been specified in the delivery
schedule you just created.

System Response

The system automatically generates the cumulative received quantity
using the document number of the last quantity received by the
customer.

How to fix this error?

Check whether the cumulative received quantity proposed by the system
is correct. If it isn't, overwrite it manually.

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.