Heroku - Error when installing heroku-toolbelt in Xubuntu 12.04

One of the first thing I have to do when starting working with heroku is to install Heroku Toolbelt at https://toolbelt.heroku.com/debian. But, when I ran the command:

wget -qO- https://toolbelt.heroku.com/install-ubuntu.sh | sh

 It raised an error:

Failed to fetch http://toolbelt.heroku.com/ubuntu/./foreman-0.60.0.deb  Size mismatch
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

I'm running on a Xubuntu 12.04 machine.

I've looked around the Internet and found some solutions but It did not work at all. 

I took a look at the script (https://toolbelt.heroku.com/install-ubuntu.sh):

echo "This script requires superuser access to install apt packages."
echo "You will be prompted for your password by sudo."

# clear any previous sudo permission
sudo -k

# run inside sudo
sudo sh <<SCRIPT

  # add heroku repository to apt
  echo "deb http://toolbelt.heroku.com/ubuntu ./" > /etc/apt/sources.list.d/heroku.list

  # install heroku's release key for package verification
  wget -O- https://toolbelt.heroku.com/apt/release.key | apt-key add -

  # update your sources
  apt-get update

  # install the toolbelt
  apt-get install -y heroku-toolbelt

SCRIPT

Everything is normal as you can see.

Actually, when I installed the heroku-toolbelt, It will installed several packages:

libyaml-0-2

libruby1.9.1

ruby1.9.1

heroku

foreman

So, I installed all the packages but foreman (because foreman raised error):

$ sudo apt-get install libyaml-0-2 libruby1.9.1 ruby1.9.1 heroku

Then, I install foreman packages through gem:

$ sudo gem install foreman

And done.