Serial Number won't work when registering product

I got a Blackwidow Elite a while back and I'm going in and registering all of my razer products in the warranty tab. It says my Serial Number is unknown. It's registered in Synapse but not under the warranty tab. I've tried looking at the box and under the keyboard and tried every variation of 1s and Is - 0s and Os. None of them work. Can't contact support because I need the SN.