Program suggests installation of package that does not exist

I tried to run seamonkey, and I get a suggestion from command-not-found that is improper.

ericu@eric-phenom-linux:~$ seamonkey
The program 'seamonkey' is currently not installed. You can install it by typing:
sudo apt-get install seamonkey
ericu@eric-phenom-linux:~$ sudo apt-get install seamonkey
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package seamonkey is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'seamonkey' has no installation candidate
ericu@eric-phenom-linux:~$

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: command-not-found 0.2.46ubuntu6
ProcVersionSignature: Ubuntu 3.2.0-32.51-generic 3.2.30
Uname: Linux 3.2.0-32-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.0.1-0ubuntu14
Architecture: amd64
Date: Sun Nov 11 12:14:00 2012
InstallationMedia: Xubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US:en
 TERM=xterm
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: command-not-found
UpgradeStatus: No upgrade log present (probably fresh install)