Problems setting up a RoR server

Hi,
I'm trying to launch my new RoR site but I've some problems with my
server.
On the the test server of my website developer everything works just
great but not on my official VPS.
This is the link to the test server http://first-link.digiti.be, and
if you than click for instance if you click on Administratie on the
left menu and then on Database Entry it will go to
http://first-link.digiti.be/nl/administratie/database_entry .
But if you do the same thing on my VPS (http://beta.first-link.be) it
will go to
http://beta.first-link.be/firstlink/public/nl/administratie/database_entry
, so it adds /firstlink/public which I do not want.

These are the specs of my VPS:
Fedora Core 6
PLESK 8.3
Apache

If you need more information just ask.

Thank for your help.