Crash when attempting to draw prizes.

[zephyyrr]

URL: https://donations.esamarathon.com/admin/draw_prize_winners
How to replicate: Go to the Draw Prize Winners view and click the button.

Error: KeyError at /admin/draw_prize_winners
Traceback:

Environment:


Request Method: POST
Request URL: https://donations.esamarathon.com/admin/draw_prize_winners

Django Version: 1.9.13
Python Version: 2.7.14
Installed Applications:
('django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.sites',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.admin',
 'post_office',
 'paypal.standard.ipn',
 'tracker',
 'tracker_ui',
 'timezone_field',
 'ajax_select',
 'mptt')
Installed Middleware:
('django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.locale.LocaleMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.common.CommonMiddleware')



Traceback:

File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py" in get_response
  149.                     response = self.process_exception_by_middleware(e, request)

File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py" in get_response
  147.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/usr/local/lib/python2.7/dist-packages/django/contrib/auth/decorators.py" in _wrapped_view
  23.                 return view_func(request, *args, **kwargs)

File "/usr/local/lib/python2.7/dist-packages/django/contrib/auth/decorators.py" in _wrapped_view
  23.                 return view_func(request, *args, **kwargs)

File "/var/www/tracker/tracker/admin.py" in draw_prize_winners
  1023.     if form.is_valid():

File "/usr/local/lib/python2.7/dist-packages/django/forms/forms.py" in is_valid
  161.         return self.is_bound and not self.errors

File "/usr/local/lib/python2.7/dist-packages/django/forms/forms.py" in errors
  153.             self.full_clean()

File "/usr/local/lib/python2.7/dist-packages/django/forms/forms.py" in full_clean
  363.         self._clean_form()

File "/usr/local/lib/python2.7/dist-packages/django/forms/forms.py" in _clean_form
  390.             cleaned_data = self.clean()

File "/var/www/tracker/tracker/forms.py" in clean
  499.             map(lambda x: models.Prize.objects.get(id=x), self.cleaned_data['prizes']))

Exception Type: KeyError at /admin/draw_prize_winners
Exception Value: 'prizes'