ProFTPD server - multiple ports, same IP address

I am having problems with ProFTPD server, because I am not able to set it to work correctly when multiple ports are active (IP address is the same).

In my proftpd.conf file, I have added this section:

 <virtualhost 0.0.0.0="">Port                        2122
    Umask                       022
    ServerName                  "Example"
    DefaultRoot                 /home/usr1/www/example1
    UserAlias                   fuser usr1

    # Valid LOGINs
    <limit login="">AllowUser usr1
        DenyALL</limit></virtualhost> 

So, when I try to establish connection to port 21, everything is ok, and I get directory listing. But when I try to establish connection to port 2122, it connects, but I get an error 500 Illegal PORT command at the very end.

In Linux Firewall ports 21 and 2122 are opened.

This is what I get when execute netstat -lpn | grep ftp

tcp6       0      0 :::2122                 :::*                    LISTEN      30597/proftpd: (acc
tcp6       0      0 :::21                   :::*                    LISTEN      30597/proftpd: (acc