Someone has to help me here. I just tested my gift certficate function. But it appears that instead of decreasing the price, it is increasing it!!

Why would this happen?

Let me give an example:

Sub-Total: $39.95

00Flat Rate (Best Way): $5.

TAX 7.0%: $2.94SG

Gift Certificates: -$10.00

Total: $66.96

I am running Zen cart1.3.8a and have not done any modifications to the gift voucher component at all.

Many thanks if someone can help me out on this one - Im sure you will agree, my customers are not going to like this one bit..