Subdomain works only localy

[marclar]

I made a subdomain (sub.mydomain.com), that should point to some webpage on my server.
How I did it?

1. httpd.conf:

<VirtualHost *:80>
ServerName www.emanuel.si
DocumentRoot /opt/lampp/htdocs/
</VirtualHost>

<VirtualHost *:80>
ServerName kud.emanuel.si
DocumentRoot /opt/lampp/htdocs/kud/
</VirtualHost>

/opt/lampp/htdocs is my /var/www, and don't ask why

2. ISPConfig
I have a root site in ISPconfig, which was suppose to be my root webpage (emanuel.si). Under that site, I added co-domain:
hostname: kud
domain: emanuel.si
create DNS:yes
create DNS MX: yes

RESULT:

kud.emanuel.si opens a webpage which is located in /opt/lampp/htdocs/kud/ , but only from computers in my network. If for example my neighbour types that page, he gets an error (the page does not exist).
Im sure that has something to do with DNS but I dont know what...
What am I missing here?

Tnx for help..