Can't access to my domain: BIND DNS with Webmin

Hi everybody,
i'm a newbie of sys administration so to everyone should answer me, just TNX!

I've bought a VPS in Ubuntu just a week ago and i've installed on it Webmin to configure my server.
It works great and i've installed every module i need there (apache, php, and so on...).

After that i could access to my server via browser with no problem.

Then i've tried to configure via BIND my domain but it seems not work. I've follow DEVSHED guide to do it, but if i check my configuration with this: http://www.intodns.com/rivapaolo.com

Any suggest for WHY not works?

Tnx a lot for everybody.
Rgds.
Paolo.