How come I can not activate my Virtual Python Environment with 'source env/bin/activate' command?

I realize I had to do

jem@jem-laptop:~$ ls
Desktop    examples.desktop  Public           shortener.rb
Documents  Mac4Lin_v1.0      ruby-1.9.1-p378  Templates
Downloads  Music             rubygems-1.3.7   Videos
Dropbox    Pictures          setcolors.vim    virtualenv.py

And here we see virtualenv.py. From here I just had to

jem@jem-laptop:~$ virtualenv ENV
New python executable in ENV/bin/python
Installing setuptools............done.

And then

jem@jem-laptop:~$ source ENV/bin/activate
(ENV)jem@jem-laptop:~$ deactivate
jem@jem-laptop:~$ 

Solved :)

In 2.7 version I used this command:

$ cd project_name
$ virtualenv venv --distribute
$ source venv/Scripts/activate
(venv)

I usually do it this way:

$ cd the_project_dir
$ . bin/activate
(the_project)$ _

I need to be in the project directory anyway to go on with the work. Obviously the_project_dir is the name of a directory where you have created a virtualenv.