apt-get in postinstallation in kickstart

[tuxico]

hello ubuntu addicts,
I need some with kickstart.

I want to install an openssh-server during the installation of ubuntu.
But with "apt-get install openssh-server" in the post-installation
part of kickstart , nothing is installed.

The others commands in my post-installation worked, like the
modifications of /etc/fstab.
I tried to use :
wget -P /o http://192.168.2.5/ubuntu_client_install/openssh-server_3.9p1-1ubuntu2_i386.deb
dpkg -i /o/openssh-server_3.9p1-1ubuntu2_i386.deb
(192.168.2.5 is a local webserver)
But some problems linked to the dependencies....

any ideas ?
I really need this apt-get in kickstart :-)
Thanks in advance.