|Try shutting the windows firewall off. |
Also, make sure your game is running in "host" or "server" mode so that it too is listening for connections on the correct port (TCP port number 25565)
If it still doesn't work, then it's likely you've misconfigured the port forward.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.