Hi Sue--
I ran your iCal export through a validator, and it comes out clean, without errors. I also created a Google subcalendar using the iCal feed URL for your account, and it read the feed without error.
Can you please test using Google calendar? On the left side of the calendar there should be a list under "My Calendars" and below that "Other Calendars" with a '+' next to it. Click the '+' and select "From URL", and then copy the URL from the WheresTheGig export page that is displayed after clicking . "Export" => "To Calendar Feed" => [Show Gig ICal Feed]. Please get in touch if you have any questions about this.
If it loads into Google Calendar, then we'll need to track down the problem with your other calendar client.
--Ethan