Purchase order from Sales order Margin issue

Hi Everyone,

why when i try to generate an PO from SO, the system takes Price list + Margin of items at PO from SO
for example:

this SO contains item price list = 13.5

with margin 12.5% = 13.5LE * 12.5% = 1.690LE

when we create a PO from this SO, the price come with it’s margin

while i had created pricing list that work only with Selling module

thank you