SAP Message VW664 - Split not possible for shipment &1, deliveries &2

Diagnosis
Splitting the selected deliveries is not possible because the shipment<(>&<)>V1<(>&<)> with the selected deliveries <(>&<)>V2<(>&<)> islinked to a transportation chain. Shipment <(>&<)>V1<(>&<)>, however,is already completed and can no longer be changed.

System Response
The split cannot be executed for the selected deliveries.

Procedure
Revoke the selection for the deliveries <(>&<)>V2<(>&<)> and restartthe splitting process.