Accepted calendar invites notification.

I am using iPhone 4S on iOS 6.0.1.

I find it weird that when I send out calendar invites to my friends I don't receive any notification on their reply for that invite.

For example:-

My wife accepted the invite but I do not get any notification she has replied "Accepted" unless I go into the calendar and view that particular event I have created to invite her.

My notification is turned on even at locked screen so I should be able to receive all notifications for the calendar but I didn't get the notification from her Accepted reply.

Anyone having the same problem? Anyone knows how to set this right?

Thanks!