Recompiling VIM: apt-get can't find source code?

Recompiling VIM: apt-get can't find source code?

I'm trying to recompile VIM with clipboard support and I'm attempting to
follow this guide.
The trouble is that when I do: sudo apt-get source vim
I get E: Unable to find a source package for vim, although the package
name was auto-completed and exists if you type sudo apt-get source
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By the way, before I started, I did sudo apt-get remove vim.
Any ideas how to proceed?
I'm using Ubuntu 12.04 LTS.