Coupon removed after checkout

[bboom]

On two different webshops I have problems with coupons. I can add the coupon and the discount is added successfully but after I clicked the checkout button, I come at the confirmation page and the coupon is removed from my cart. When I re-add the coupon at the confirmation page the discount is added again and it is oke.

This practice is not clear for customers I tink. Is this a bug in VirtueMart?

I'm using virtuemart 3.0.8 on joomla 3.4.3