unplanned delivery cost

Dear experts,

when i am doing payment to the vendor system calculating discount on total amount based on payment terms (for example MIGO amount is 1000 and in MIRO i added 100 rupees as unplanned delivery cost). i want to calculate discount only on 1000 not on 1100. can any one tell how to do it plzz.

can any one respond on this?

Edited by: ksuncara on May 11, 2011 1:46 PM