I am not sure what is wrong, but I cannot verify the theme.
Your code is valid, but it looks like it has already been used on another site. You can revoke and re-assign within your Themeco account
So I have gone to the account, and there is no feature to revoke. Just able to change the URL. Its a new site with no other plugins or, for that matter, anything but wordpress.
I would be grateful if someone could advise.