Tarka Serial

[jkcpa]

So, my Tessarisis came with a Tarka inside. I got the Tessarisis open (excellent puzzle) and went to register my Tarka. When I put in the number on the outside of the Tarka, it tells me it's not a valid number. My eyesight isn't that bad, but I took a picture of it on my phone and blew it up and double-checked. I have the correct number, but the system won't recognize it. Who can help me get this corrected?