On my Genos, the label on the underside of the keyboard has a stuck on label which says 'Genos', and underneath that is the Serial Number both as a barcode and text.
When I received the keyboard, also included was an 'Online Member Product Registration' document showing the Product ID.
I don't recall if I needed to use this to register the keyboard. I think that I just entered 'Genos' as the model and then the serial number.
I have just logged into my account and as a test, started the process to register a new product. When I entered 'Genos' as the model, a box appeared below the entry field which showed Genos. This was only an information box - there were no 'clickable' objects in it, so it looks as if 'Genos' was accepted as the model.
The box to enter the serial number is further down the page, and was not visible on my laptop screen until I scrolled down. Could it be that you haven't scrolled down to find this box?
Once the keyboard has been successfully registered you will get an email with a promo code to use on the Yamaha Musicsoft site which will adjust the cost of one of the 'offer' packs to zero at the checkout stage. It worked fine for me. I was also able to get free Genos versions of all the Yamaha Premium Packs that I had previously purchased for my Tyros4.
Regards
Ian