Gift Voucher - Payment Still Requested

Hi folks..
I'm new here so I'll do my best to describe my problem..

Version 1.5.4, New Install, No mods done at all.
I manually created a Voucher
I can apply the voucher fine.

During the checkout the voucher will show the total as being zero.
when I confirm the order it brings me to PayPal anyway and asks for the order total less the gift certifacate value.
PayPal is the only payment gateway.

I've checked any options I can see in the Admin function..

Help appreciated on this as I'm near ready for rollout and would like it working..

Thanks,
Brian.