python - Flask Extension not found in Virtual Environment after transfer to new computer -

i'll preface admitted may not totally understand inner-workings of virtual environments, please forgive me if i've committed utter fail.

for desktop (mac os x 10.7 + python 2.7) have virtual environment houses web application i'm building in python (using flask framework). wanted work on laptop, zipped directory contained virtual environment , code , transfered on laptop (mac os x 10.7 + python 2.7).

after unzipping, tried launch application , received following message:

(venv)****:*** ***$ python runserver.py traceback (most recent call last): file "runserver.py", line 2, in <module> weirdcanada import app file "/users/****/****/weirdcanada/weirdcanada/__init__.py", line 3, in <module> import weirdcanada.views file "/users/****/****/weirdcanada/weirdcanada/views.py", line 18, in <module> flaskext.principal import anonymousidentity importerror: no module named flaskext.principal 

i tried pip install flask-principal , after installing it, re-ran application , received same error. checked site-packages in virtual environment , flask-principal installed.

my questions:

1. am misunderstanding point of virtual environments? should able copy virtual environment on have? thought consistency , portability main features.
2. how can fix this?

thanks help!

i pretty sure changing line:

 flaskext.principal 

to

 flask.ext.principal 

should work.

i have 3 virtual environments installed on system(mac osx 10.6 + python2.7). created new virtualenv , code working fine in other virtualenv not working here , in case flaskext.wtf culprit.

i checked versions of flask , extensions in both virtualenvs , same version problem out of question.

it not make sense why should happen anyways try , reply back.