ActualShipment does not replace Shipment ship units

Cancelled Shipment ship units are not deleted from OTM when interfaced from JDE. Transmission contains Release and ActualShipment Transactions. Release Transaction is processed successfully .But ActualShipment transaction error out with unique constraint on s_ship_unit table.Odd part is that when <ShipmentStop> tag for stop sequence 1 is removed from the XML, Transmission is processed successfully and both order release and shipment ship units are deleted for cancelled lines.

Details of ActualShipment XML as follows

Transaction Code : RC ; Managed Child - ShipmentStopDetail & ShipUnit ; Int Command Name : MapTempReferences & DetermineShipUnitDropOff

Any input on the above issue is more appreciated.Thanks.