First I develop a new model ( custom stamp tax) . And it work without problem when I create inv from accountig model .
But the problem is when i want to create the inv from S.O the line of my custom stamp tax dont appear in journal items lines..(entry) .. but if i change the date of inv the line of my custom stamp tax appear and work very well ..
I want to show this line auto ... please help me

so you need to start from this :)
custom module. what and how it impact? what means custom stamp from odoo side? tax id or what? where it comes if you create from accounting?

Its just a monetary field his name is Stamp_tax calculate : he is working like this => if customer has a stamp_tax then in invoice => total amount =total amount +stamp_tax value ... so here I _inherit from account move ..and when i create invoice in accounting model everything works perfect . The problem is when i create invoice from sale order in the invoice lines in journal dont appear this stamp_tax . And when I change anything in invoice like change date of invoice or anything the line of stamp_tax work .