Supervisord的Python导入错误

我正在使用超级用户来将celery作为守护程序运行，但这给了我error ImportError: No module named tasks worker。我可以在没有监督的情况下从shell运行它。我的超级用户配置文件如下：

[program:celery]
directory=/home/yongfengzhang/videomaker
environment=PYTHONPATH="/home/yongfengzhang/videomaker:/home/yongfengzhang/videomaker/videomaker:$PYTHONPATH",DJANGO_SETTINGS_MODULE="videomaker.settings"
;command=/home/yongfengzhang/Envs/videomake/bin/celery -A "tasks worker" --loglevel=INFO --concurrency=4
command=celery -A "tasks worker" --loglevel=INFO --concurrency=4
process_name=%(program_name)s ; process_name expr (default %(program_name)s)
numprocs=1
user=yongfengzhang                  ; setuid to this UNIX account to run the program
stdout_logfile=/home/yongfengzhang/logs/celery/celery.log
stderr_logfile=/home/yongfengzhang/logs/celery/celery.err
autostart=true
autorestart=true

因此，在下面/home/yongfengzhang/videomaker我tasks.py定义了celery实例和任务功能（此处未显示）：

app = Celery('tasks', backend='redis://localhost', broker='amqp://myuser:bloomsky@localhost:5672/myvhost')

在此文件夹（~/videomaker）中直接运行celery时，一切都很好。这Envs/videomake是我的virtualenv所在的位置。__init__.py文件夹中有一个。任何输入将不胜感激。非常感谢。