Many packages are in the universe repository. Here are instructions on how to enable this repository. It is not enabled by default.
Here are two methods. One does it all in Synaptic, while the other uses the command line. The end result of both methods is the same.
It is important to understand that you should not remove or replace anything. You must only ADD the universe entry. Do not remove main, or you won't be able to install main packages.
Be sure to read the section about universe at this web page: Components.
These instructions are for Sounder CD 9 and later; earlier releases have main restricted universe lines, which should be changed to simply universe.
Method 1: Using Synaptic
1. Start Synaptic by selecting:Computer -> System Configuration -> Synaptic Package Manager
2. In Synaptic, bring up the repositories window: Settings -> Repositories
3. You will see two repositories of type deb with the URL http://archive.ubuntu.com/ubuntu
one of which is checked. Select one or the other, and see which one shows Section(s): universe
(It is probably the second one.) Enable that one. Now do the same thing for the two repositories of type deb-src with the same URI given above. Click on OK.
4. Now, still in Synaptic, click on Reload to update your local copy of the package database.
Method 2: Using the Command Line and an Editor
1. Edit the file /etc/apt/sources.list. Uncomment the two lines that end with universe. (You will see a comment about this in the file.)
2. In a terminal, give the command sudo apt-get update to update your local copy of the package database.
You may also want to enabled multiverse and restricted while you are enabling universe. Just add the text "multiverse restricted" after "universe" in the sources.list.
http://www.ubuntulinux.org/support/docu ... 5359349801