Registered Ghost 15 turns to trial after Win10 upgrade

Hi, I have three copies of Norton Ghost 15.  I upgrade one of my laptops from Windows 7 to Windows 10 pro today.  This laptop had a registered copy of Norton Ghost 15 on it.  After the upgrade, the icon in the tray says "Product trial expires in 30 days".  This didn't overly concern me as I still have the Product keys associated with my 3 copies.  Unfortunately none of them work.  The error I get back is "Cannot activate this product using license key <my license key>.  The license key is not valid.  Please enter the correct license key".   Please advise what I should do to correct this problem.  I can provide 1 of the 3 license keys I have if that will help.