How do I activate previously purchased Version 7 on new computer

[Susan Moeller 0]

My laptop crashed and OS had to be reinstalled.  My serial number is recognized on your site when I went to there to deactivate it for the new activation, but the current version of Nitro Pro is not accepting my serial number, stating it does not exist.  How do I activate previously purchased Version 7 on my restored laptop? 

[Leslie V. 0]