Help please-Norton antivirus subscription error

Hello thanks for helping me, I am currently having trouble with a norton antivirus subscription:

Recently I have had to format my computer resulting in a complete loss of all my programs and files (such as my registered norton antivirus). However I kept my registration key and have just installed norton antivirus with a trial period to be able to activate my registration key. Upon entering my registration key I am confronted with the following message : " You have exceeded the number of allowable installations for this product", I don't see how that is possible for this is the same computer on which I installed my previous version of norton antivirus with the same key. Moreover on my norton account my 2 year subscription is not there anymore but a purchase of a 2 year subscription is visible in order history! I would like to solve this issue as soon as possible please.
Thank you, James