Wrong calculation for coupons, please help

Hi !

I'm using ZC 1.3.5.

I create a coupon to give 10% discount one like this:
Coupon Name: test
Coupon Desc: blabla
Coupon Amount: 10%
Coupon Minimum Order:
Free Shipping:
Coupon Code: test
Uses per Coupon:
Uses per Customer: 1
Start Date: 2006-12-01
End Date: 2006-12-31

and that's it, right ?

Then I go to the shop and purchase 5 items like this:
1 x Always blue Array 70:- (correct)
1 x Always pink Array 45:- (correct)
1 x Always White Array 50:- (correct)
1 x Be white Array 45:- (correct)
2 x Blue cocoon Array 120:- (correct)

Sub-Total(incl. 25% VAT): 330:- (correct)
VAT: 66:- (correct)
Discount Code: test : -26:- (WRONG, should be -33, 330 - 10% = 33)
Total: 271:- (WRONG, should be 297:-, 330 - 33 = 297)

I have read that there are some errors in the code somewhere but it's not clear where and I can't find a correct fix for this.

Can anyone please tell me how to fix this problem asap or please guide me to where to download a fix ? I have a coupon out now and I need this to be fixed as soon as possible. Customers are ordering and it's a bit awkward that the invoice is wrong... Please, please, please help...

My Discount Module settings :
Discount Coupon

This module is installed: true
Sort Order: 280
Include Shipping: true
Include Tax: false
Re-calculate Tax: Standard
Tax Class: --none--

I hope you have all the info you need...

Regards,
Typhoon

(to late for a change...)

I found out how ZC calculate... If it helps...

Total = 330
ZC's calculated discount: -26
Correct discount: -33

330-26-33 = 271

But ZC should, of course, only calculate 330 - 33...

I really need help with this...

/Typhoon