Virtualenv's env activated but still running system's python

I created a Virtualenv env and activated it but it still running the system's python

(myenv) dangtrinhnt@genius:~$ which python
/usr/bin/python

So I did the following to fix that:

1. Delete the broken Virtualenv env:

sudo rm -rf /my/venv

2. Create a new one with "distribute" parameter:

virtualenv myenv --distribute

3. It works now

(myenv) dangtrinhnt@genius:~$ which python
/myenv/bin/python