can't add ie document

[gelina10011001]

When I want to add iedocument. The error happens.Why?
IndexError at /admin/corpus/iedocument/add/

tuple index out of range

Request Method: GET
Request URL: http://127.0.0.1:8000/admin/corpus/iedocument/add/
Django Version: 1.8.14
Exception Type: IndexError
Exception Value:

tuple index out of range

Exception Location: /home/futureai/iepy_environment/lib/python3.6/site-packages/relatives/templatetags/relatives.py in related_objects, line 61
Python Executable: /home/futureai/iepy_environment/bin/python
Python Version: 3.6.5
Python Path:

['/home/futureai',
'/home/futureai/hijk/bin',
'/home/futureai/anaconda2/envs/py3/lib/python36.zip',
'/home/futureai/anaconda2/envs/py3/lib/python3.6',
'/home/futureai/anaconda2/envs/py3/lib/python3.6/lib-dynload',
'/home/futureai/iepy_environment/lib/python3.6/site-packages',
'/home/futureai/iepy_environment/lib/python3.6/site-packages/iepy/webui']

The reason is in this line: {% related_objects adminform.form.instance as related_objects %}