I decided to upgrade my 64-bit 10.04LTS to 12.04, but have hit a simple problem. I'm trying to do a network upgrade using Update Manager by following the instructions at https://help.ubuntu.com/community/PreciseUpgrades under "Network Upgrade for Ubuntu Desktops 10.04 LTS to 12.04 LTS". In "Software settings", "Release upgrade" is set to "LTS releases only" and the system is fully up to date. At this point, after checking again for updates, there should be an upgrade button, but no luck. Any ideas?
I've tried various restarts, and if I set "Release upgrade" to "Normal releases" the button appears offering 10.10. That fails for other reasons though, and in any case I prefer to make one upgrade instead of four. I've seen posts that make me think this has been done successfully recently, e.g. http://ubuntuforums.org/showthread.php?t=2059473 , so can anybody help?
Thanks a lot!