brand new keyboard. cynosa lite. serial number not recognized by site

im trying to register this keyboard. its asking for a 15 character code which i am inputting correctly and its not going through.
the support page asks for the same serial but of course has the same problem which leads me here where i shouldnt have to go for something so simple.

on the keyboard it shows S/N:xxxxxxxxxxxxxxx and i know the S/N: isnt included. just the x's code.
ive tried uppercase and lower. changing the "S" to a "5" when its clearly an S.
any help would be great. thanks.