Nginx can not be enabled for a domain that alias has an Apache website

hello.
I have Debian. I use Nginx on port 80 and Apache port 81.
in virtualmin when creating the domain. I put in “Setup website for domain” and “Enable Nginx website”. for the creation error:
“Failed to create virtual server: Nginx can not be enabled for a domain that alias has an Apache website”.

My config /etc/apache2/ports.conf
Listen *: 81