django-crontab works manually but not automatically

Question

I hope i could get some help I have installed the django-crontab and created a cron task like the following inside of my cron.py inside my_django_app in django:

import redis
def hello():
    redis.set("hello", "world")

the above code works perfectly when I run python manage.py crontab run (cron hash)* and the key set successfully inside redis but the task doesn't run automatically have you had any similar experience? Note: I am using linux and python version 3.9 and django 3.2.3