Comment 5 for bug 1486599

Please disregard my previous comment.

In one of your messages, you said that "I am trying to update repositories for ubuntu 11.04".

Ubuntu 11.04 is no longer supported (End of life).
http://fridge.ubuntu.com/2012/09/17/ubuntu-11-04-natty-narwhal-reaches-end-of-life-on-october-28-2012/

Because of this, you can no longer update your repositories and install updated software. This is also the reason why Cube always fail to download new repository lists.

I suggest that you upgrade to Ubuntu 12.04 or 14.04. These are long term support (LTS) versions that are supported up to 3 years, if im not mistaken.