[Chicago] virtualenv not showing installed packages

[Oren Livne]

Dear All,

I'm trying to configure my python environment called "ober" in a cluster 
machine. I did the following:
- downloaded virtualenv.py
- virtualenv.py ober
- . ober/bin/activate
- pip install numpy --upgrade (installed 1.6.2)

However, the numpy version is still shown as 1.5.1, because

(ober)[livne at ibicluster python]$ echo $PYTHONPATH
/clusta/livne/ober/util:/clusta/livne/ober/impute:/clusta/livne/ober/network:/clusta/livne/ober/famplot:/apps/rhel5/x86_64/MACS/MACS-1.4.2/bin1/lib/python2.7/site-packages:/apps/rhel5/x86_64/Python/Python-2.7.1/lib/python2.7/site-packages:/apps/rhel5/x86_64/CEAS/CEAS-Package-1.0.2/lib/python2.7/site-packages

does not include my virtualenv's site-packages directory, even though

(ober)[livne at ibicluster python]$ which python
/cihome3/livne/python/ober/bin/python

Any advice?
Thanks so much,
Oren