Upgrade of Ubuntu 10.04 to 10.10 fails

Dear Friends,

I request apologizes about my bad English, and I request apologizes if this question was answered in the past. I did a search through the forum and I did not find anything.

Im running Ubuntu 10.04.4 LTS, and I want to upgrade to 10.10, and later to 11.04, 11.10 and finally to 12.04.

I followed the instructions in the page: http://library.linode.com/upgrading/upg … 0-maverick">http://library.linode.com/upgrading/upgrade-to-ubuntu-10.10-maverick

But when I do "do-release-upgrade --proposed", the result is the following message:

__Checking for a new ubuntu release

Failed Upgrade tool signature

Failed Upgrade tool

Done downloading

Failed to fetch

Fetching the upgrade failed. There may be a network problem.__

I'm not sure if Ubuntu 10.04 has reached his end of life and maybe it is not possible to upgrade it to 10.10, or if I'm doing something wrong.

Any help?

Thanks in advance

Cylon.