Facebook Login Error Assert access-token is none.

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it seems everything is configured perfectly. But I wonder why they can't get access-token. I got warning from sanction library:

warn('sanction.client.Client is deprecated, please use sanction.Client')

AssertionError at /account/signin/complete-oauth2/
No exception message supplied
Request Method: GET
Request URL:     /account/signin/complete-oauth2/?code=AQCZs-Vol2DIevS-AeV3nmzNycUj75rdqpg9bvK7fNqrxtYRzRPVJNWxpZztPXZorqg8wfutFJ_tFuskis1mnazVWw
Django Version: 1.8.18
Exception Type: AssertionError
Exception Location: /Users/dhluong/mylab/aenv/lib/python2.7/site-packages/sanction/client.py in request_token, line 126
Python Executable:  /Users/dhluong/mylab/aenv/bin/python
Python Version: 2.7.10
Python Path:    
['/Users/dhluong/mylab/adsbasics',
 '/Users/dhluong/mylab/aenv/lib/python27.zip',
 '/Users/dhluong/mylab/aenv/lib/python2.7',
 '/Users/dhluong/mylab/aenv/lib/python2.7/plat-darwin',
 '/Users/dhluong/mylab/aenv/lib/python2.7/plat-mac',
 '/Users/dhluong/mylab/aenv/lib/python2.7/plat-mac/lib-scriptpackages',
 '/Users/dhluong/mylab/aenv/Extras/lib/python',
 '/Users/dhluong/mylab/aenv/lib/python2.7/lib-tk',
 '/Users/dhluong/mylab/aenv/lib/python2.7/lib-old',
 '/Users/dhluong/mylab/aenv/lib/python2.7/lib-dynload',
 '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7',
 '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin',
 '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk',
 '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac',
 '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages',
 '/Users/dhluong/mylab/aenv/lib/python2.7/site-packages',
 '/Users/dhluong/mylab',
 '/Users/dhluong/mylab/aenv/lib/python2.7/site-packages/askbot/deps']
Server time:    Tue, 16 May 2017 08:09:46 -0500