How to add parts to my startercharacter?

When I try to add ears to my startercharacter , it just drops off when I play the game.

https://gyazo.com/cab0043246fbe2bf22bcdfc718a4787c <--- How its suppose to look like (Not playing yet)

https://gyazo.com/088a4eaddb448abd52bf931e63155011 <--- How it looks like (Playing)

The ears doesnt attach to the head but just falls off. Please help.