Not receiving invites in calander

Hi,

It appears that I am not receiving invites from my wife and vice versa when creating new events in calendar, I have a iPhone 5 and my wife has a 3GS both with the latest software, I creat the event add the invitee send it and it never appears on the wife's calendar, I also have a iPad and they are not appearing in that calendar also and both the iPhone 5 and iPad use the same iCloud account.

Please help