HELP PLEASEEE!!!!! With iMessage :(

I have the 3rd iPad.. I have my iMessage on but i cant send messages to other iPhone users in other countries.. I have them added in my contacts, and i used to be able to talk to them through iMessage but then one day i got a red exclamation mark next to their name and wasn't able to press the send button.. I have a blackberry and i have whatsapp installed and i have their numbers added the same way as in my iPad and they do appear there and i can talk to them too but not on iMessage... It just stopped working.. Do u know of any solution to this?

Have them check iMessage on their end. There are things that can happen to get it turned off and stuff.

Yeah it seems like it would be something on their end, as long as you have the full phone number in your contacts such as the "+(country code) (area code) (phone number)" it should go through to them. Maybe they changed their number or phone, or disabled iMessage completely. Also, find out if they have their apple I'd email set up to receive iMessages through there (so instead of sending it to their phone number, you'll send it to their Email address), see if it will send that way.