I am sorry to say the way in which this thread is dragging should have been locked. I have already indicated the issue is in your pricing procedure if the value is not fetching correctly in sale order. If I take the example from your original post, your pricing procedure should be as follows:-
100::::::PR00::::::Price:::::::
110::::::ZK20::::::Discount:::100
120::::::Net Value::::::::::::::100::::120
If at all you have any other condition types before this net value, the logic should be as above. Also, it is noticed that your discount condition type ZK20 is checked for "Condition Index" and I am not sure, why it is checked. If it is a normal discount, this box should not be checked.
G. Lakshmipathi