I have a problem. I have installed the contrib and it works with fixed amount. But the problem is that i can't use the exclude part. I'm trying to exclude all manufacturers except one. Buying a product with that included manufacturer works with the discount but i'f i'm trying to buy from another manufacturer i don't receive any error message, i just proceed to the next checkout without any discount. I'f i'm buying from both an included and excluded manufacturer i do receive the discount. Anyone who knows what the problem might be?