Cancelling a PO released from a Blanket Order does not credit back the Quantity/Cost to the Blank

Hi there

I am looking  for the proper set up (if there is any)  that could allow  the quantity/cost/amount  in  a Blanket  order be credited  back  when PO's lines (released  from this Blanket Order) are cancelled (for instance, opening the PO lines  and Using  Cancel line hyper button)

It is supposed to work basically....but can't make it (Xe or 9.))

Thanks for your help