Recently I have encountered an issue with my IPad2 that is frustrating. When I attempt to IMessage my daughter on her Iphone4 I get a red exclamation with the message she is not registered with IMessage. I can IMessage both of my sons and my wife with no problem. All 3 of them can IMessage my daughter with no issue what so ever. I have had this IPad2 for a year and had no trouble until a couple weeks back. I am not sure what to do to fix this problem and any help would be appreciated. Tony