Product key is not accepted

I purchased a Norton 360 antivirus (3 pcs) a couple of days ago.. I enter the product key and it does not accept it.. My previous antivirus is the Norton Premium 360 (again for 3 pcs) which expires in 1 day.. The same purchased antivirus has been installed successfully on 2 other computers.. Please advise as I will not be protected as of tomorrow.

Please advise as soon as possible.

Thank you in advance,

Sandie