To sort the calendars there is the "list permanently" button. Instead you should be able to just press the calendar and drop it where you want it. This way you don't need the extra button and it is more consistent with the events and you can also drag and drop.

Steps:

1. You have 2 different calendars and want to change the order.
2. You click on the last calender, hold the mouse and drag it to the top.

Actual result:
Nothing happens.

Expected result:
The calendar moves up to where you release the mouse.