Agree with the above comments.

Just so you know what is going on (assuming no damage to your hub mentioned above):
If the cog is not properly tightened on install, it will tighten itself up more as you ride it. When this happens the lock ring is no longer tight against the hub, allowing for the cog to tighten and loosen when you accelerate and brake. Eventually this will cause your lock ring to come loose (it already was loose, but it will become more noticeable) and will ruin the threads on your hub for the lock ring. At that point the hub is only good for the freewheel side (assuming you have a flip/flop)