Incorrect Authorization Key: For Multiplayer

[KnightMason]

So using Hamachi we got LAN servers to showing up after we tried and failed to connect a simple 2 player game between friends with online servers.
Now a new problem. And I have a feeling it's related to me buying this game as a gift for my friend, using my account so it thinks we have the same key. Or maybe we're over thinking it.

So, I can see my friends server in a LAN game when he attempts to host, and he can see mine if I host.
But we can't connect to either. Even though we are on different internet connections. (But in the same apt building.)

This is what happens. While attempting to connect, it shows "Checking serial number..."
Then after a few moments it says "Incorrect Authorization Key"

What exactly is the Authorization Key?
Is that the key we have linked to our software?
It should be separate keys since we have separate games right?
Even thou I gifted it, with my account, for a friend?

We just want a solution so we can host our own LAN party games in our area... it could lead to a lot more people buying it if it's fixed, whatever the issue is... ;)

:Edit:
By "Gifting" I mean i payed for another copy, as a gift to him.

[brideson]

There is no shortage of keys (this was a massive problem for Frontlines. See: http://forums.steampowered.com/forums/showthread.php?t=1036513)

And gifting only means that you pay for it :D

I will look into this for you since I do not like hearing about people not being able to play. Also this is a bump for others to help

[Earthfrui]

I am having the same problem. Get "Incorrect Authorization Key" and I bought the game just for myself. Doing a complete re-download now to see if that fixes it.

[Apollo]

i still cant play multiplayer or go past level 7 despite buying the game for full price. it wont activate with the key i was given from steam. there are quite a few ppl having the same problem as me and i made a master thread on it

[Lithen]

Similar issue, we are in the same room on a LAN but we can't connect.
We get an error saying "Couldn't connect to server"
Any specific ports or anything?
Is there a workaround with hamachi?

We have steam copys of Warband and M&B

Cheers