vCalendar Support

I've been trying to add vCalendar support in lwt (auto import of events into your personal desktop calendar). So far the results I have, is that if you download the .ics file and double click it on the desktop, everything is fine. However if I try to get the associated app with text/calendar to open it. I get an "Object not found" error in Outlook.

I'm sending the header:
header("Content-Type: text/calendar");
header("Content-Disposition: inline; filename=MyvCalFile.ics");

from within my php script.

Has anyone done this?
Did you get Outlook to import the file from within a web page?