Google Calendar, iCalendar Validator but not bloody Apple iCal

I've got a public ical at: http://m.fwckungfu.com/calendar.ics

This works in Google Calendar and in the iCalendar Validator but when I try to import this as a file in Apple iCal I get this message:

"Error subscribing to the calendar

Data downloaded from http://m.fwckungfu.com/calendar is not valid."

WTF? Who's ass have I not kissed to get this working in Apple iCal? Does anybody know any reason why Apple iCal is being so trixy?