teniworks

I've been trying to purchase the Socially Viral theme which originally appeared for me as $47 to purchase. I also have a $5 credit in my account as well. However, when I originally went to check out the cart showed the final total as $42. Then I went back to another page on the site and then came back to the cart and it is now showing $47 as the total cost and not applying the credit. Can someone please explain what is going on? Thanks!