php5 session problem when setting up lamp

[febius]

Hi everybody,
I'm trying to install a LAMP server on a Ubuntu 6.06 Dapper Drake distro, just to make some tests locally with some CMS and try to build some web service on my own.
I installed the ubuntu-lamp package (wich includes the latest version of php, mysql, apache and various modules as php5-session and php-mysql). Apache starts correctly, and php too, at http://localhost/ I can see everything on /var/www/; I activated the mysql extensions on php.ini and I made everything I learned on the various tutorials on the web but as I try to connect to http://localhost/phpmyadmin I have a problem: "cannot load the session extension,...."
I don't know what to do, somewhere on internet I read that is a problem of php5 and that php 4 works fine but I anyway need php 5 to do my job.
Can you help me? Thank you