coupon, gift voucher can't be applied..

i am using open cart ver 1.5.2.1 my website www.ypcomputer.com

i have problem when i use coupon n gift voucher.. when i click apply. message appear it's been applied.. but at total parts not get any discount.. point to use it's work.. only both coupons n voucher cant be used..

please help me..

same problem here. This link refers to a solution I am having my tech person try:
http://www.richardcarterconsultancy.com ... ncart-1-5/