My new computer has win 8.1 & now new norton product key from Staples will not work

i just bouught a new computer  from Staples runing win 8.1 & now my new norton's 3 install product key also bought at Staples will  not be accepted on the new computer. however, i am able to get to take on my laptop running win 7 & also on my older computer running win xp. can someone help me solve this problem? thank you for your time