How do I make the OAC5 window for barcode pop up for transaction KO01?

The user will use transaction KO01 (Internal Order). For barcoding purposes they should be getting a pop up window on saving the transaction. I believe an entry in transaction OAC5 should bring up the window. They enter the barcode which will be used for scanning later. This works for other transactions. I have also entered the right object type BUS2075 for internal order. I have no idea on why the pop up window on saving does not appear.