Current order cumul. qty is smaller than cumul. qty received by customer

What causes this issue?

The current total cumulative delivery order quantity is smaller than
the cumulative quantity received by customer - the system has created a
negative quantity in transit.
Scheduling agreement &V1&
Item &V2&
Contract release type &V3&
Cumulative quantity received &V4&

System Response

The system rejects the entry.

How to fix this error?

Check both cumulative quantities. These form the basis for creating the
quantities to be delivered.
Review whether the total cumulative delivery order quantity or the
cumulative quantity received by customer have to be corrected.
If the release was applied using EDI, proceed as follows:
If the total cumulative delivery order quantity must be corrected,
enter a corresponding delivery order correction in the dialog, and
apply the IDoc afterwards as new.
If the cumulative quantity received by customer must be corrected,
apply the IDoc in the foreground processing as new, and correct the
cumulative quantity received by customer accordingly.
If the release is edited manually, enter a corresponding delivery order
correction beforehand, or, when entering, correct the cumulative
quantity received by customer.

Error message extract from SAP system. Copyright SAP SE.