Приводите полный трейсбек. Вообще не понятно где конкретно ошибка была.
AttributeError at /admin/set_test/grouptest/add/
'NoneType' object has no attribute 'save'Request Method: POST
Request URL: http://127.0.0.1:8000/admin/set_test/grouptest/add/
Django Version: 1.8.8
Exception Type: AttributeError
Exception Value: 'NoneType' object has no attribute 'save'
Exception Location: C:\Python27\lib\site-packages\django-1.8.8-py2.7.egg\django\contrib\admin\options.py in save_model, line 1080
Python Executable: C:\Python27\python.exe
Python Version: 2.7.10
Python Path: ['C:\\inetpub\\wwwroot\\Django\\sbdi_sys',
'C:\\Python27\\lib\\site-packages\\distribute-0.6.14-py2.7.egg',
'C:\\Python27\\lib\\site-packages\\setuptools-19.6-py2.7.egg',
'C:\\Python27\\lib\\site-packages\\psycopg2-2.6.1-py2.7-win32.egg',
'C:\\Python27\\lib\\site-packages\\django-1.8.8-py2.7.egg',
'C:\\Python27\\lib\\site-packages\\pillow-2.8.2-py2.7-win32.egg',
'C:\\Python27\\lib\\site-packages\\python_docx-0.8.5-py2.7.egg',
'C:\\Python27\\lib\\site-packages\\django_admin_tools-0.7.2-py2.7.egg',
'C:\\Python27\\lib\\site-packages\\isapi_wsgi-0.4.2dev-py2.7.egg',
'C:\\Windows\\system32\\python27.zip',
'C:\\Python27\\DLLs',
'C:\\Python27\\lib',
'C:\\Python27\\lib\\plat-win',
'C:\\Python27\\lib\\lib-tk',
'C:\\Python27',
'C:\\Python27\\lib\\site-packages',
'C:\\Python27\\lib\\site-packages\\win32',
'C:\\Python27\\lib\\site-packages\\win32\\lib',
'C:\\Python27\\lib\\site-packages\\Pythonwin']
Updated 29 Feb. 2016, 15:44 by Origin.