Still not working

I installed Coupon Pro. Installation Check shows 'Installed' by all lines.
Running Virtuemart 1.1.9.
Dit some customisation as described here: forum.virtuemart.net/index.php?topic=52919.0
Checked the discount activation in vm config.
Created a coupon

Still nothing!
Please help.

go to admin->awocoupon->configuration->coupon code error description tab
and change the error messages to something more identifiable, this should tell you why the coupon is failing.

It's working. But does a customer have to know the coupon code? I want automatic apply a discount.

Yes, this is a coupon component, so customers are required to put in a coupon code. You could probably customize Virtuemart to auto process one coupon code pretty easily.