As stated in the steps I gave you you need to use Product Key on COA sticker which legally must be on any machine in order for Windows to be preinstalled upon it.
The key scanned from HD is the factory mass activation key which cannot be used for activating a clean reinstall.
Check your computer on all sides for a COA sticker like this. On notebooks it is on bottom or under battery:
You would need to use the Factory Recovery disks if there is no COA sticker, but if you have to order them you should ask your OEM why there is no sticker and report it to MS Customer Service since it is not a legal preinstall of Windows 7.