Gear S AT&T Unlocked but does not recognize my carrier

I unlocked my gear s via cellularunlocker.net but my carrier does not recognized by my gear s. Anyone have a solution to this. My idea is that network band does not support. Im using GSM carrier so is there any way that it can be changed? Please help me out. I actually paid to get it unlocked so i dont wont it to go to waste. Thanks alot.:(