I am using 11.10 and I really want to update to 12.04 but it's impossible. I cannot see it in the update manager (I did select the option for the releases). I tried sudo update-manager d, and sudo-apt get upgrade and sudo apt-get upgrade release d but nothing. And sudo do-release-upgrade is not working as well! (I get "no release found" message.)

So finally I did put on a live USB and when I boot, I click on install, then it's telling me that I do have 11.10 and I can select for erase all and install Ubuntu 12.04 or I can install along 11.10 and the second option to update 11.10 to 12.04 is grey. I cannot selected it! Why? Am I running out of options?

What else can I do to upgrade to 12.04?