django custom filter invalid error

我自定義了一個(gè)filer但加載的時(shí)候報(bào)錯(cuò)了

目錄結(jié)構(gòu)
templates/

index.html

ticket_track/

models.py
views.py
templatetags/
    __init__.py
    my_filter.py
    

ticket_request_system/

settings.py
    

index.html

{% extends "base.html" %}
{% load my_filter %}

{{ ticket.params|my_tag:"domain" }}

my_filter.py

#!/usr/bin/env python
#coding:utf-8

from django import template
import json

register = template.Library()

@register.filter
def str_dic(format_string,args):
    return json.loads(format_string)[args]

register.tag('my_tag', str_dic) 

settings.py

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'ticket_track'
]

報(bào)錯(cuò)信息如下：

TemplateSyntaxError at /tickets/working

Invalid filter: 'my_tag'

Request Method:     GET
Request URL:     http://ticket.web.isd.com/tickets/working
Django Version:     1.11.1
Exception Type:     TemplateSyntaxError
Exception Value:     

Invalid filter: 'my_tag'

Exception Location:     /usr/local/lib/python2.7/site-packages/Django-1.11.1-py2.7.egg/django/template/base.py in parse, line 515
Python Executable:     /usr/local/bin/python2.7
Python Version:     2.7.12
Python Path:     

['/data/release/ticket_request_system_test_env/code_alt',
 '/usr/local/lib/python27.zip',
 '/usr/local/lib/python2.7',
 '/usr/local/lib/python2.7/plat-linux2',
 '/usr/local/lib/python2.7/lib-tk',
 '/usr/local/lib/python2.7/lib-old',
 '/usr/local/lib/python2.7/lib-dynload',
 '/usr/local/lib/python2.7/site-packages',
 '/usr/local/lib/python2.7/site-packages/setuptools-25.2.0-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/requests-2.14.1-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/Django-1.11.1-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/pytz-2017.2-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/enum34-1.1.6-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/redis-2.10.5-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/supervisor-3.3.2-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/meld3-1.0.2-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/ChatterBot-0.6.2-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/SQLAlchemy-1.1.10-py2.7-linux-x86_64.egg',
 '/usr/local/lib/python2.7/site-packages/python_twitter-3.3-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/pymongo-3.4.0-py2.7-linux-x86_64.egg',
 '/usr/local/lib/python2.7/site-packages/nltk-3.2.4-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/jsondatabase-0.1.7-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/chatterbot_corpus-0.0.1-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/requests_oauthlib-0.8.0-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/future-0.16.0-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/six-1.10.0-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/oauthlib-2.0.2-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/db.py-0.5.3-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/pybars3-0.9.3-py2.7.egg',
 '/usr/local/lib/python2.7/site-packages/pandas-0.20.2-py2.7-linux-x86_64.egg',
 '/usr/local/lib/python2.7/site-packages/MySQL_python-1.2.5-py2.7-linux-x86_64.egg',
 '/data/release/ticket_request_system_test_env/code_alt']

Server time:     Fri, 15 Dec 2017 11:15:20 +0800

我是按照django的官方文檔配置的..這個(gè)錯(cuò)誤為啥有，麻煩大神幫忙看看