This no longer works.
There are two possible reasons for this:
- Microsoft has disabled the tool from accepting PKs due to every Win8 user being upgraded to 8.1. New customers purchasing Windows 8 would be upgrading from the store and not from this tool.
- A Windows 8 activation key can only be used once within the 8 installer, after that, the user will need to use a generic key to install Windows 8/8.1.