"cannot open display: :0.0" error when using schroot

[Aniruddha <mailing_list@orange.nl>]

I have set up a schroot using this guide: 
http://alioth.debian.org/docman/view.php/30192/21/debian-amd64-howto.html#id292205 , but for some reason when I try to run a program I get the following error:

> ~$ schroot -p nero
> W: Group ‘sbuild’ not found
> I: [sid chroot] Running command: “nero”
> 
> (nero:456): Gtk-WARNING **: cannot open display: :0.0

I have set up a succesfull schroot before, the only difference now is
that I use sudo.

"DISPLAY=:0" doesn't work either:

> (sid32)root@Desktop:/# export DISPLAY=:0
> (sid32)root@Desktop:/# nero
> 
> (nero:4231): Gtk-WARNING **: cannot open display: :0

My schroot.conf
> [sid]
> description=Debian sid (unstable)
> location=/var/chroot/sid
> priority=3
> users=rleigh,aniruddha
> groups=sbuild,aniruddha
> root-groups=root
> aliases=unstable,default

Regards,

Aniruddha