Cannot update or refresh cart

Hi i've got everything pretty close to being set up except i'm having a problem with the final steps. I can ad events to my cart from either the categories list or the event page but i can not change anything in the cart. Add more, check out, refresh etc. DO NOT work. I keep getting this message: Secure Connection Failed

please help!

Can you send me the link to your site so that I can check it ?

Tuan