discount coupon rejected by Linkpoint

I am using zencart v1.3.9 and I have a discount coupon set up. When purchasing in the store and using the discount coupon I get the following message:
'Congratulations you have redeemed the Discount Coupon'

Then when completing the transaction via credit card the following message comes up:
'Your card has been declined. Please re-enter your card information, try another card, or contact the store owner for assistance.'

The Linkpoint Data Debug email says 'Charge total must be the sum of subtotal, tax, value added tax, and shipping.'

I called my gateway and they say that zencart is not sending out the correct information, ie. not including the discount amount so the transaction is being kicked back.

I'd really appreciate some help with this. It's pretty embarrassing to give a client a discount coupon and then have it not work!

Which version of 1.3.9?

My apologies. I was incorrect. It looks like I'm using v1.3.8 [2009-02-11 17:42:00].

A large number of improvements were made in v1.3.9, including several to the linkpoint_api module.

I recommend upgrading.
In the meantime you might try and see whether this temporary update might help briefly: http://www.zen-cart.com/forum/showthread.php?p=563490#post563490

Thanks I'll try the patch until I'm able to update.