Problems with taxes after discount

Joomla! 2.5.11
Virtuemart 2.0.20b
Using One Page Checkout for VirtueMart 2
Using AWO Coupon Pro 2.2.2

Hi, I have a problem with taxes.
After applying the coupon the amount of taxes in invoice remains unchanged


Product 250,00 €
Total Tax 45,08 €
Coupon (ADWME2014)-240,10 €

Total: 9,90

How can I fix the problem?
thanks

Hello,

By invoice you mean the backend order detail right? and not an external invoice?

In AwoCoupon, do you have calculate discount before tax set to yes?