Links in ical -- don't work?

I'm using ical right now to track my daily activites/to do items, and when i enter a url in the appropriate section, it turns blue. I assumed I could click on it to go tot he appropriate site, but nothing happens, either in the event entry or a to do entry. I also noticed that if I type an email address in the notes section, it doesn't change color at all. Can anyone tell me how to fix these problems?