Unable to ADD Shipment Refnum Qual

Hello,
am trying to add Shipment Refnum Qualifier so that i can trck few details while doing shipment tracking , Path as below
Shipment--ShipmentManagement--Events--Add Event For Location

Please let me know where do i need to add refnum qualifier for this , Adding details in Shipment Ref num in Power Data is not helping me

any suggestions will be very appreciated.