ical problem - double-click event is for wrong calendar

I have several custom icloud calendars - one is a work calendar, but not the default work calendar (it's titled something like "ABC Company"). Another is titled "Hard Calendar" and this one contains my 'set in stone' activities.

Problem: when I uncheck all my calendars except "ABC Company", and double-click in the weekly view, on Monday, to enter an event, the Hard Calender is automatically activated and the event is created for the wrong calendar - and all the other events show up for the Hard Calendar as well.

Whether I double-click or press the Plus button for a new event, the behavior is the same.

I deleted the hard calendar and the same behavior happens, only now the new entry activates the built-in "ToDo" calendar, not my "ABC Company" calendar.

Any ideas about what's wrong?

Thanks in advance!

It's not the check mark that determines that. (it turns the events on or off in the calendar view)

What you need to do is make sure the one you want to add to is the one highlighted.