Ubercart

I am trying to use the uc_discount_alt module to create discounts and i have used the attributes module to have different product versions, i have set unique SKU's but the problem is that the discounts module doesn't pick up the alternate SKU's

If i set the discount to the main product SKU and then change some of the options it notices from the other end that there are different SKU's but i would like to be able to apply discounts to the different attributes

any help would be much appreciated

thanks

Jacob