Shopping Cart Price Rule

[Stokes82]

We have set up a shopping cart price rule that lets the customer take off $40.00 when entering the code 2015SOCCER.  The coupon works well until you buy an item that is under $40.  If you buy something that is $38.00 it leaves the grand total at a -$2.00.  Of course we know the order will not process with a negative amount in the total.  Is there a way to make sure the total will be zero when ordering an item under $40?  Thanks for any help you can give me.

Shawn

[Stokes82]

Ok update on this... I have figured out how to get it to a total of zero.  When I try to place the order though it will say "invalid amount for capture".  Any one know what this is all about?

I also see that in mage/authorizenet/model/Directpost.php there is code stating if it is at a total of zero it cant capture.  

public function capture(Varien_Object $payment, $amount)
{
if ($amount <= 0) {
Mage::throwException(Mage::helper('paygate')->__('Invalid amount for capture.'));
}

Is there a work around for this?  Really need to be able to let my customers use this coupon to get money off or even for free.