Pokemon omega ruby: Shedinja

Hi I am currently playing Pokemon omega ruby on the 2ds. I heard from a friend that shedinja is a good pokemon, but I don't know how to evolve from nincada to shedinja. I always get a ninjask. I would like some help on how to get a shedinja.Thanks in advance! :)

Bulbapedia:http://bulbapedia.bulbagarden.net/wiki/Shedinja_%28Pok%C3%A9mon%29Bookmark it for future reference...

ok thank you for your help i will try again.