[Answered ]-Django external app installation "Error: No module named nested-inlines"

This is a guess, but that app is probably not available on your PYTHONPATH. You may need to tell Django to look in there to find applications you want to use. Something like the following might work to make it so that your settings.py can import the app for your django project.

settings.py

import sys
sys.path.append("/Applications/djangostack-1.4.7-0/python/lib/python2.7/site-packages/")

## After which you can include it in your installed apps:

INSTALLED_APPS = (
'nested_inlines',
'other apps',
'etc',
)