Yeah, I've seen people post varying results in numerous threads.

Some installations just accept the key, but you need to activate manually rather than automated.

Mine wasn't having a bar of the key when I did the first installation, no idea what might cause the variable result, just happy it was so easily sorted out!

Now to find some drive rails to remount my old hard drive, I'm sure a spare set came with the case two years ago, but I've no idea where they might be.... sigh