Availability check 'KP' , confirmed qty, credit blocked but increase value in FD32

Hi experts,

   I have some question about availability check 'KP'.

   Once i created sales order with mateial  ATP = KP, i got the credit exceed message.

   Once i saved this sales order, confirmed qty = sales order qty, Order status = Credit bloked but in FD32  value of this sales order  take into account (increase credit exposure).

    My requirement is  if credit blocked , confirmed qty must equal sales order qty but value of this sales order must not effect to credit exposure in FD32.

    I  try to change configuation in  OVZ2 , like this

         AV = KP

         TotalSales = A

          TotDlvReqs = A

          No check = X

    Once create sales order again, it working fine.  I'm not understand why

Total sales order requirements  is related with credit exposure ????

Best Regards,

Jenny