I spoke to support and here's the deal... on the product packaging of their SSD's, they leave off the last letter of the serial number, the 15th digit, to prevent people from registering an unopened box. If you already installed the drive, you'll need to take the drive back out of your system and read the full 15 digit serial number off the SSD itself, OR, you could attempt to guess that last 15th digit and just try 27 times 
Also, if you are trying to use the Samsung Magician software to read the serial number using that software... and if you have a 4K monitor, you will find that the software doesn't work. Apparently they have been trying to fix that also as it's been a problem in the last couple versions of the software back as far as 7.3.0 and is still broken in version 8.0.0 (latest as of this writing).
Thirdly, the support guy also asked me to wait a bit before trying to register because the entire product registration site is experiencing API errors and their support center is getting flooded with calls.
