Register a Product

Hi, I'm new here, i just buy a Blackwidow keyboard, and i want to register de product but, the web says me: the serial number of the product is unkown. Do anyone know if have to write the "S/N:" before the numbers or write "0" instead of "O" or somthing like that, that is giving me the problem? (pd: i'm spanish, sorry if somthing i said is wrong)