Why doesnt the gift voucher substract

[bkng]

I'm trying to install the gif voucher mod (3.2) and everything seems to work fine but..............

 

the Order total amount doesnt substract the gift voucher amount.

 

So it shows the amount e.g. 25 and then 10 fot the gift voucher and the amount stays 25 while it should be 15.

 

I'm at a loss.

 

Help, Help, Help. Please