Issue with discount and margin

I have created a base pricelist, above which I created a pricing rule for margin of 10 rs.

Until here, the system works fine but now when I want to add a discount of 5% over the price above, system does something funny and changes the discount percentage to zero every time I save the order. So, I created another pricing rule with additional discount of 5%. Now when I save the order, this pricing rule is either not applied or added twice… very confusing