[Nix-dev] Nix-channel does not work for me

[Pjotr Prins]

Now the openssl.org site is down, and for the first time I have an
up-to-date kernel, I tried installing a channel for pre-built
binaries. With nix 0.13 following the manual:

  nix-channel --add http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable
  nix-channel --update
  nix-channel --list     

renders

  http://nixos.org/releases/nixpkgs/channels/nixpkgs-unstable

And

  nix-env -qa vim

renders

  vim-7.2
  vim-7.2-huge-X11-python-tcl

however

  nix-env -b -v -i vim

just renders some files it parses, but nothing happens. E.g.

  (...)
  evaluating file `/home/wrk/.nix-defexpr/channels/nixpkgs_unstable/pkgs/build-support/fetchurl/mirrors.nix'
  evaluating file `/home/wrk/.nix-defexpr/channels/nixpkgs_unstable/pkgs/stdenv/common-path.nix'

Why is it not working? 

Pj.