Emoji's not working

[avester]

I downloaded the newest software for my galaxy s4 (4.4.2) and it has a new feature which are emojis. however, most of the time when I use them in a text, my friends (which have iphones and the same phone as me) say that they come up as question marks. I have no clue how to fix this and I really just want them to be visible on the other end. Everytime I type them, it always shows up on my part that it sent as the actual emoji. Few times have I been able to send them and they actually come out. please help!!