Invoice

I want to ask about invoice ,, when i changed prices the new price updating on product and services for every client but the system create invoice with different amount in case of discount only EX. client service cost 1299 and he has discount with 10% so the invoice should be with 1299 and discount 129 so finial cost should be 1169.10 but the invoice created with 1443.60 and discount with 144.36 so the final amount was 1299 which is the service cost without discount.