Still not working, sorry. There is no virtual host section in my .htaccess.
I can't understand the problem: during installation, the demo sales channels are set up by the install script perfectly. I don't understand, why another new sales channel can't be set up automatically in the correct way. Be it as it is, I'll stop trying osCommerce and give it up. It seems to me that it's not the right software for me.
Thank you for trying!