If I add a product to my cart, then apply a coupon, it works.
If I add a second product to my cart, then apply coupon, the cart gets emptied out.
Also, if I try to delete one item or change quantity from cart, the cart goes empty.
Please try? www.shurrsuccess.com
Looks like you have something wrong with your install, or other problem. I suggest trying to find what is wrong specifically or different with your system.