Impossible to upgrade Virtualmin

Hi there!

I have Virtualmin 3.93 GPL installed with Webmin 1.620 under Ubuntu 10.04.
I honestly don’t remember how I installed Virtualmin though. Whether I did it manually or using the install script.

My sources.list file contains the lines :

deb sarge contrib
deb sarge contrib

As you can see I already have the latest Webmin version running and I had no problem getting the package update notification everytime a new release comes out.
All my system is up to date and running apt-get update && apt-get upgrade gives me 0 packages to update.

The problem is that I’m stuck with Virtualmin 3.93 and don’t get the package update notification for a newer version neither did I succeed to upgrade it using apt-get install webmin-virtual-server which is telling me that I already have the newest version.

Any idea on how to troubleshoot and fix that?