When I run `python manage.py runserver`, everything starts out fine, but then I get a `SystemCheckError` stating that Pillow is not installed; however, Pillow is definitely installed on this machine.

This is the error I receive:

> 
> Performing system checks...
> 
> 
> Unhandled exception in thread started by Traceback (most recent call last): File
>  "/usr/local/lib/python2.7/dist-packages/django/utils/autoreload.py",
>  line 225, in wrapper
>  fn(\*args, \*\*kwargs) File "/usr/local/lib/python2.7/dist-packages/django/core/management/commands/runserver.py",
>  line 110, in inner\_run
>  self.validate(display\_num\_errors=True) File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py",
>  line 468, in validate
>  return self.check(app\_configs=app\_configs, display\_num\_errors=display\_num\_errors) File
>  "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py",
>  line 527, in check
>  raise SystemCheckError(msg) django.core.management.base.SystemCheckError: SystemCheckError: System
>  check identified some issues:
> 
> 
> ERRORS: recipes.Recipes.primary\_image: (fields.E210) Cannot use
>  ImageField because Pillow is not installed.
>  HINT: Get Pillow at <https://pypi.python.org/pypi/Pillow> or run command "pip install Pillow". recipes.Recipes.thumbnail\_image:
>  (fields.E210) Cannot use ImageField because Pillow is not installed.
>  HINT: Get Pillow at <https://pypi.python.org/pypi/Pillow> or run command "pip install Pillow".
> 
> 
> 

I'm running this on an Ubuntu machine. Any ideas what's up?