[Scribus] Problem with 1.3 (Debian/Knoppix)

[Le Tigre]

Hi everybody.
I am using Knoppix 3.7, and I used apt-get to install Scribus 1.2.2 (thanks to
Oleksandr Moskalenko!) - and it's ok.
I tried to install also the 1.3.1 with deb        
http://debian.scribus.net/debian/ testing main non-free contrib.

Many packages were missing: I used apt-get and installed them.
When I'm doing /opt/bin/scribus, it says:
Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified

scribus: cannot connect to X server :0

And I absolutely dont know what to do.

As you can see, I'm an absolute Newbie...
Thank you.