Pricing Rule issue

Dear All,
I have an issue with the selling cycle…
when issuing a sales order, a price list for the customer is applied, and the customer discount applied based on the pricing rule is applied based on the condition in the pricing rule applied for the price list an customer., the problem is when doing a delivery note or sales invoice the discount removes it and have to remove items or customer name and add again to apply on each transition ( Delivery note Sales invoice,) !!! while if I do ignore the selling rule and put the discount manually in the sales order then the discount is added automatically in the delivery note and invoice !!!
what is this problem and how to solve it?
M Shehata

Attached example, the order submitted with rate in the price list and pricing rule applied but when create delivery note or sales invoice from the sales order the pricing rule not applied !! Must remove items and add again which is not logical!!
Pls help how solved

Delivery note & sales invoice from sales order
How solve this bug?!!!