Adding coupon code at checkout

Hello CS-gurus,

I ask for help in adding a place for my internet customers to add a coupon code and receive a discount. I have added the coupon code but nothing seems to come up at checkout. A gift coupon box DOES come up. I added the code but it does not work.

Much thanks for any help.

Catalog->Promotions->Add Cart Promotion

Set the availability dates and make sure its active. Go to Conditions to set the type of discount the coupon is for.