definitely this thread should be in Microsoft's Wireless Troubleshooting , that if he really own the Router
which i believe he isn't.
back to your problem ... the ideal conclusion is that when you were trying to capture the Handshake someone (maybe you) was trying to connect to the AP thinking he may generate handshake and speed up the process but unfortunately aircrack-ng print back the Key you inserted.
pay your Bill mate and live free on the internet