Why is there an exclamation point beside my ical invitees?

Are you using Microsoft Exchange with iCal? Do you have Outlook installed? If so try doing it again with Outlook running in the background. I don't know why but there can be server issues with iCal and Outlook working together. I could also be the default account you are using with iCal.

I'm also having this problem. I have a calendar "on my mac" and 3 other calendars linked with my me.com account. When I try to add an invitee to an event, I see a question mark in front of their name. If the contact has multiple email addresses in my Addy book, it will not recognize the one I select.

I have SL 10.6.8. I don't remember if I did much calendar work before the upgrade, but now, I can't add any invitees. Could use some help if anyone knows.

I think I may have found the answer to my question. I guess I wasn't familiar with the symbols in iCal, but the Question mark means, "You added invitees to an event but you haven’t sent the invitation, or you sent the invitation but no one has responded or there are mixed responses." I got this answer from the iCal 4.0 Help documentation. The real problem is, mobile is my stand in calendar from 9 to 5. If anyone is acknowleging my invites, I don't own an iphone or any other mac product, so them replying to my invite only sends an email but doesn't update my mobile calendar until I go home, fire up the iMac, open mail, and download the "accepting iCal notification" in their email.

Laborious if you ask me, but at least it answers why the question mark is showing next to the names when I add events.