problem starting kde

[Etienne Gos <gos@noos.fr>]

Bonjour
I have a problem starting kde.
I installed task-kde with dselect from http://kde.tdyc.com/debian potato
main crypto optional
Everything seems to be ok.
But once I start (debian panel with blue background), login user, chose
kde2, password, there is a problem: the kde2 window doesn't open
correctly, just a blue window with a little window where I can tape
orders.

I looked around, and found out that:
task-kde ist not correctly installed:
# dpkg -s task-kde
Package: task-kde
Status: install ok not-installed

# apt-get install task-kde
Sorry but the following packages have unmet dependencies
task-kde: Depends: kdebase but it is not going to be installed
                Depends: kivio but it is not going to be installed
E: Sorry, broken packages

# apt-get install kdebase
Sorry but the following packages have unmet dependencies
kdebase: Depends: libgl1 but it is not installable
E: Sorry, broken packages

# apt-get install kivio
Sorry but the following packages have unmet dependencies
kivio: Depends: libggi2 (> 1:1.99.2.0b2.1) but it is not installable
        Depends: libgii0 (> 1:0.6) but it is not installable
        Depends: libgl1 but it is not installable
E: Sorry, broken packages

I tried to reinstall with dselect, but it did not change anything.

Is there a link between my problem to start kde2 and this broken
packages? And what can I do?
Thanks in advance
Etienne Gos