python - pip: Could not find an activated virtualenv (required) -

i trying instal virtualenv and/or virtualenvwrapper on mac osx 10.8.3

i have been fighting python last 2 days. able install python 2.7.4 using brew. before had virtualenv installed using easy_install. tried uninstall it, trying computer in same situation 1 of colleagues. maybe uninstalled success, maybe not. don't know how test it. supposed install virtualenv using -

pip install virtualenv 

but gives me -

could not find activated virtualenv (required). 

pip install virtualenvwrapper gives same output.

also variable: pip_respect_virtualenv null:

echo $pip_respect_virtualenv 

how can solve issue?

thanks

open ~/.bashrc file , see if line there -

export pip_require_virtualenv=true 

it might causing trouble. if it's there, change false , run -

source ~/.bashrc 

if not, run export pip_require_virtualenv=false terminal.