PI value gets disappeared from AUFK after saving in COR2 tcode

Hi Experts,

   I have have weird situation. I have created a custom Packing Instruction field in one of the tab of process order in COR1 tcode. After releasing and saving of process order, i am extracting the packing instruction and updating it in AUFK table through BADI 'WORKORDER_UPDATE' in method AT SAVE. The value gets inserted into table AUFK after release and save. The value of packing instruction is visible in the field added at screen while opening COR2. But while i again click on save button in COR2 tcode , the inserted valueof packing instruction in AUFK gets disappeared.

Please help how to get through this.

Thanks

shahab