Problems with a website when I change the domain.

Hello I have a server with ispconfig.

I have a website with a oldDomain, and I want to move to newDomain.

I have create an alias from the oldDomain to the newDomain.

I'm trying with this code in the .htaccess

Code:

    RewriteCond %{HTTP_HOST} ^(www.)?olddomain.com$ [NC]
    RewriteRule ^(.*)$ http://www.newdomain.com/$1 [R=301,L]

The problem is that It takes a url like

Code:

    http://www.olddomain.com/node/255 

to

Code:

    http://www.newdomain.com/index.php

And I want that it moved to:

Code:

    http://www.newdomain.com/node/255

Any idea what's going on?

Thanks

Oskar