Awo coupon starter

Hello,
VM 266
hello since I use your extenion I've create coupon code and it works well but when I enter a wrong name of the coupon I don't have error message like wrong coupon...on the page.
I have a write page on the page : website/cart/checkout.html, its not normal.

Hello,

Are you using any one page checkout extensions? Or is it default virtuemart checkout?

Hello it is default VM checkout
Please go on website www.perledoree.fr and you can make a test.

Hello,

I just tested the page, I entered the code "wrongcoupon", and I get the error message:

Ce code chèque boutique n'est plus en vigueur. Veuillez en essayer un autre, s'il vous plaît.

Maybe I do not understand the problem?

Thank you for your answer,you have understand my problem don't worry. I don't know what is happen too ?? because before when we enter wrong coupon we have white page on the checkout and know I have error message says that its not a right coupon so it seems to be ok...