How to upload ICS (iCal) files?

I click “Add Media” and select my ICS file (exported from iCal).

I get: “File type does not meet security guidelines. Try another.”

Is there another way to upload this type of file? I’d like our fans to be able to download and import our calendar of events into their electronic calendars. I download and import ICS files quite frequently on Facebook, and find it very handy.

Thank you.