show original price after member log in

[design160]

hi, I'm new for prestashop. I want to show original price after member log in. For example:
Original price:$100
Member group: VIP
Group Reduction: 50%

I want to show:
original price : $100
current price: $50

But so far, after member log in, the original price would be $50, same as current price.

Can anybody help?

Thanks a lot.