group discount not showing on checkout

The group discount amount is not showing on the checkout page. I have assigned a 10% discount to a group and upon checkout the discount is applied but does not show on the page. This causes my cc merchant (linkpoint) to disapprove the transaction because of what it sees as a matamatical error. Below is the explanation given for disapproval:
SGS-002301: Charge total must be the sum of subtotal, tax, value added tax, and shipping.
An exapmle: with group pricing discount 10%
subtotal: 500
Tax: 0
VAT: 0
shipping:0
Charge Total: 450
This transaction will be disapproved because the Group Discount although calculated is Not showing.

When I use the coupon mod for a similar transaction, the coupon discount shows and the transaction is approved.

Sorry for the long winded explanation.
If anyone can help me correct this problem it would allow me to use the group pricing mod.
Thanks in advance,
ooakllc