Because they are not using Elite for this game. Ghosts has its own program that you have to download via smartphone. Just go to your smartphones store (ex. playstore for android or the apps on your iphone) and type in Call of Duty, it should be one the first apps to come up. Its is NOT Elite so DONT click on that.
My fingers are crossed that this clan stuff works a heck of a lot better than Elite did.
Elite was basically unusable for almost a full 7 or 8 months during MW3. The only way that we could get it to work at any sort of level, was if I gave my log-in details to someone in the States, because mostly everyone in Canada (around the Toronto area) just couldn't get the damn thing going.
But yeah - let's hope. I've sent invites out to over 40 friends for my clan, and yet I've only had 7 ppl tell me they actually got it.