Pip doesn't install packages to activated virtualenv, ignores requirements.txt
Struggled with some variation of this issue not long ago; it ended up being my cluttered .bash_profile file.
Make sure you don't have anything that might mess up your virtualenv inside your .bash_profile/.bashrc, such as $VIRTUAL_ENV or $PYTHONHOME or $PYTHONPATH environment variables.
I am attempting to setup a development environment on my new dev machine at home. I have just installed Ubuntu and now I am attempting to clone a remote repo from our web-server and install its dependencies so I can begin work. 
So far I have manually installed virtualenv and virtualenvwrapper from pypi and edited my bash.rc appropriately to source my virtualenvs when i start my terminal. I then cloned my repo to ~/projects/project-name/websitename.com. Then I used virtualenvwrapper to mkvirtualenv env-name from ~/projects/project-name/websitename.com. This reflects exactly the file-structure/setup of the web-server I am cloning from. So far so good. 
I logged into the dev server and activate the virtualenv there and use pip freeze -l > req.txt to render a dependencies list and scp to my local machine. I activate the virtualenv on my local machine, navigate to the ~/projects/project-name/websitename.com and execute pip install -r path-to-req.txt and it runs through all of the dependencies as if nothing is wrong. However, when i attempt to manage.py syncdb i get an error about not finding core django packages. What the hell? So i figure somehow Django failed to install, i run pip install Django==1.5.1 and it completes successfully. I got to setup my site again and get another error about no module named django_extensions. Okay, what the hell with it, i just installed all of these packages with pip?! 
So i pip freeze -l > test.txt and cat test.txt, what does it list? Django==1.5.1, the one package I just manually installed. Why isn't pip installing my dependencies from my specified list into my virtualenv? What am I messing up here?
-EDIT-------------
Which pip gives me the path to pip in my virtualenv
I have only 1 virtualenv and it is activated