I installed Commerce Coupon module
I didn't use the coupon percentage module. I created a custom coupon type which has 5 custom field, coupon_code, coupon_number_of_uses, coupon_owner, coupon_percentage and coupon_date. Then I created an instance of it and everything works fine, but in the checkout process page when I enter the coupon code nothing happens.when I check the ajax result with firebug, the response is empty. any idea what's wrong here?