Failed partial update

Binary package hint: update-manager

I upgraded from Karmic 9.10 to Lucid 10.04 today viacommand line "update-manager -d". When the upgrade completed, and I rebooted, I launched Update Manager. I was presented with a dialog that said I could perform a partial upgrade with a list of reasons why. I slected Partial Upgrade. I then received an error message "Cannot upgrade. An upgrade from lucid to karmic is not supported by this tool." I was surprised at this error, as there was not an option to upgra\de from Lucif to Karmic. One concern I have is that I will be unable to obtain updates to Lucid through this avenue.
1. lsb_release -rd
Description: Ubuntu lucid (development branch)
Release: 10.04
2. apt-cache policy update-manager
update-manager:
  Installed: 1:0.126.9
  Candidate: 1:0.133.9
  Version table:
     1:0.133.9 0
        500 http://us.archive.ubuntu.com/ubuntu/ lucid/main Packages
 *** 1:0.126.9 0
        100 /var/lib/dpkg/status
3. I expected to be able to donload updates for Lucic, yet Update Manager did not work as expected.

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: update-manager 1:0.126.9
ProcVersionSignature: Ubuntu 2.6.32-18.27-generic 2.6.32.10+drm33.1
Uname: Linux 2.6.32-18-generic x86_64
Architecture: amd64
Date: Mon Mar 29 20:30:24 2010
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
PackageArchitecture: all
ProcEnviron:
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: update-manager