Try retrieving your key again to make sure it is the correct one: <a href="http://www.unknownworlds.com/ns2/retrieve" target="_blank">http://www.unknownworlds.com/ns2/retrieve</a>
If it still fails drop an email to store@unknownworlds.com and im sure they will be able to help you out.
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If it still fails drop an email to store@unknownworlds.com and im sure they will be able to help you out.