Wireless Mac keyboard S/N # ?

This is a new wireless keyboard.The keybaord is randomly disconnecting then reconnecting. I've tried everything suggested to this point, and now need to talk to Support, but can't find the S/N #.

Can anybody tell me where to find the S/N #? Mac Support won't accept either of the two numbers on the bar code on the box and there is no other S/N on the keyboard itself.

Thank you,

Brian