If you are experiencing problems with the calendar and just:in, please first check the following:

• Please check if the just:in application has permissions to access the calendar application
• This setting can be found within the System Preferences - Security and Privacy
• Then switch to the Privacy tab and then choose the calendar application
• There just:in must be selected

If this is working and you are still having problems, please fo the following:

• Quit the just:in engine application
• Open the calendar application and delete all just:in related calendars, if some are there
• Open the just:in application again and check if channels are activated
• Then calendars should be created automatically

If these steps are not working, please create a support ticket.