Hello, when I want to activate channel 7.1, it says that the serial number is already used

Hello, I got an original Black Shark V2 X headset. I recently came to the site to activate channel 7.1 and I click on the serial number and the model and everything comes up, but when I enter all the addresses and countries, it says that this product is already registered. If you did not register it, please contact Razer support. Please someone help and that I have created a file in Google Driver which contains all purchase documents and serial number and headset box.