When I try and send emoji it shows as a question mark, but when they are sent to me, I get them. What could be going on?

[AC Question]

when I try and send emoji it shows as a question mark, but when they are sent to me, I get them.

when I send an emoji on TouchPal the receiver see only a question mark instead of the emoji, however when they send me an emoji I can see it. When I switch to the Samsung keyboard I can send the little green icons and they can see those. I have the Galaxy S4 Active.