django_cron run only once django

Question

Sorry for my english. I new in django, i want send email every 1 min. I found this solution i follow it. But my django_cron run only one.

i installed django_cron like this: pip install django_cron

then i added app to INSTALLED_APPS

    INSTALLED_APPS = [
       ..
        'django_cron',
'accounts',
    ...

    ]

and add to settings:

CRON_CLASSES = [
    "accounts.cron.MyCronJob",
]

then run python manage.py migrate django_cron

in app accounts i create file cron and add this code:

from django.core.mail import EmailMessage

from django.template.loader import render_to_string
from django_cron import CronJobBase, Schedule


class MyCronJob(CronJobBase):
    RUN_EVERY_MINS = 1

    schedule = Schedule(run_every_mins=RUN_EVERY_MINS)
    code = 'accounts.cron.MyCronJob'    # a unique code

    def do(self):
        print("send message")
        message = render_to_string('cron_file.html', {
            'name': '111'
        })
        mail_subject = 'Congratulations'
        to_email = 'test@gmail.com'

        email = EmailMessage(mail_subject, message, to=[to_email])
        email.send()

then run python manage.py runcrons

but message send only once when i call command python manage.py runcrons