Can't join a friend's game

[Druidic]

I'm having a problem right now. I've searched a few threads but have not found the correct requirements that match what I'm dealing with.

I have a non-Steam version of Mount and Blade: Warband, bought from the Gamestop App. I got the serial key, so I should have no problem joining. My friend is on the second computer next to this one, and he also has a serial key, but with the Steam Version that he bought from his house. He logged into his account from the second computer and downloaded the game. We decided we'd host a game that only us can play.

The problem arises here. I try to join his game after finding it from Local Area Network, but when I try to join with the correct password, it says "Incorrect authorisation key". He took the password off, and same deal.

It has nothing to do with the serial keys as far as I know, because I have checked, and the one he has is different than the one I have. Any solutions?

 

[Jacques Cartier]

Have you tried not playing with LAN? I know there is some issues with LAN I have experienced personally, as we played a mod called NordInvasion, and we would join a server at the same time and whoever joined first by a very short amount of time both of our accounts would be that person.

So I am not sure if that has to do with anything, but if you join the server at the same time it might mix up your keys.