I found another problem. I don't receive any code after payment, after the purchase is confirmed. I receive the emails of virtuemart but there is no code for the Gift Certificate.
As I don't use the front of virtuemart and don't use the product menu of virtuemart, I will tell you how I made everything.
I made exactly what you explain in the tutorial. Then to publish the gift certificates (to show them in the frontend) I went to the joomla menu where I configured the categories of the virtuemart by choosing the virtuemart component (in the menu) and then writing the category I wish that button displays.
I open the main menu in joomla, then I clicke new. In the new button/link template, I choose the type and select VIRTUEMART, then I write on parameters (on the right of the menu) in category, the number of category of GIFT CERTIFICATES, for example 2.
and I call the button/link Gift certificate. Then when I go to the frontend I click on the main menu the button/link Gift certificate and it takes me to that category on virtuemart and I see what you see in the link I send you in my last email.
So the problem is that gift certificates are not working. The images of the gift certificates are not shown and I don't receive the code of the gift certificate after the status is confirmed. (I receive the virtuemart emails telling me about the purchase and the status is changed but without any code)
The discount coupons are working well.
I hope your help, thank you very much