Wrong discount amount $

I setup a coupon with a value of $100.00.
Restricted that coupon to be valid only for the Hardware category.

If I have a product that the coupon is valid, the discount is applied, but not the total of the product, instead the total coupon amount is applied $100.00. As you can see the discount should be up to $70.95 because the coupon is not valid for the second product.

Any way to fix this?
Thanks

If you make a Discount Coupon for $100, then regardless of the price of the Product, the Discount Coupon will give $100 off the Order, when a qualified Product is in the cart ...

I also have a problem with the discount coupon's, it has always worked properly before (I did an upgrade from 1.3.9h to 1.5.1 2 months ago). I had a customer using a EUR 100,00 discount coupon on an order of EUR 113,20. However the discount the coupon gave was EUR 117,36 and total is 0,00. The strange thing there was left tax of EUR 2,29.

I tried to create a new coupon of EUR 100,00 and use it in a testorder of EUR 160,00 and it deducts EUR 117,36 also? I did some calculations and found out if I do the EUR 100,00 * 0,8520 it gets EUR 85,20. If I enter that amount as the value it works and the discount coupon takes EUR 100,00 of the order. So it calculates 17,36% more then it should (we have 21% tax in the Netherlands) and I never changed anything....

Any coupon which has a percentage (10%) discount works fine however.

Any help?

René

What are the exact settings on the Discount Coupon?

Do you have any Restrictions?

What are the settings in the Modules ... Order Total ... if you click on:
Discount Coupon ot_coupon

that show in the right panel?