Invalid URL

hi,

i really would like to test or use this plugin. however, when i try to use the shortcode in either [largecalendar] or [iCal https://mycalendar.ics] i get an “Invalid URL” error.
https://dl.dropbox.com/u/14284/screenshots/armicalerror.PNG

the link to my ical feed is in the screenshot as well. also, is there a problem in using a webcal feed from microsoft? as the address starts with “webcal://” instead of http but even the other plugins i’ve tried using have no problem with it as they either change the prefix automatically to “https://” or they allow me to change it to “https://” and it work.