Sim Not Valid on iPhone 4S?

I got it unlocked at a store. I am with Chatr so I cut the sim card myself, didn't work at the store (my mistake). They also gave me a Gevvy sim card (ios 6 version). So I got a new Sim Card and got it cut at a store, the man told me it should work but I didn't activate it yet on iTunes. I tried to but it says my Sim is not compatible. I researched online before and most people had no problem getting their sim card cut and working in their iPhones! What seems to be the problem? Could I use another friend's iPhone sim card to activate my iPhone THEN insert my cut chatr sim card? I also got the advice to use someone else's Rogers micro sim card since chatr is with Rogers, and then my chatr sim card should work.