Coupon for subscription products?
 

Hey all, to give a little insight into what I'm trying to accomplish...I am using the Paid Memberships mod with X-Payments Subscriptions to sell memberships that would renew monthly. I am trying to setup a coupon that will give any non-member a 50% discount on their first months membership dues. I have set them up in a number of different ways but every time I test the coupon at the checkout stage it gives me the error below.

ERROR: The coupon cannot be used because the applicable discount is equal to 0.

Is there a way to get this accomplished without a large amount of custom programming and added cost?