Amount not taking changes in Pricing condition

Dear All,

i have sales order 1-11-123 with three line item like 10,20,30.

only line item 30 has invoiced and others are remain same .

now when i am going to change the pricing condition (Profit margin) of line item 10 or 20, system does not taking any affect ,

please see the screen shot , here the profit margin is 24.910 % , and when i change to 25 or any value and after hitting enter value reversed to its original position means 24.910 % ,

please guide me where i am doing mistake.