Thanks a lot.
That explains everything that have happened.
I used CentOS 5.5 (32 bit) with ISPConfig 188.8.131.52 according to this guide by falko :
But I think almost all the guide still used named.conf which point their query to localhost or 127.0.0.1
Maybe they hope that we'll be able to change it according to our needs, but some people still doesn't know about this concept.
Thank you everyone!