Empty Handling Units from inbound Delivery

I am using Function Modules HU_GET_HUS , V51P_FILL_GT, HU_EMPTY_HU and HU_POST in sequence to empty Handling Unit for tr code VL32N ( Inbound Delivery) .

The HU is getting empty but the materials related to the HU under 'Materials to be Packed' is getting deleted .

Could you please help , what can be the reason or what I need to do so that materials are shown after unpack of HU .

Thanks