Spent $200 on a Razer Headset, Not Eligible for 7.1 Code

Don't get me wrong, I really, really like this headset that I bought. It's the Blackshark V2 Pro White Edition. I just realized that I might be able to get the 7.1 Surround Sound that I'm offered every time that I turn on my PC. So I went to the Razer site to get a code and that's where I discovered that my headset isn't eligible for the free code. The part that's funny is that the little brother version of my headset, the Blackshark X, which is a $50 headset, is eligible for the code. That just doesn't make any sense to me. Hoping I can get an explanation is to why this is.