Cant invite specific friend to campaign.

I have 2 friends who play this game. Both downloaded it from steam but for some reason I can only invite one of them to campaign.

I have a campaign running and I try to invite my friend but the "invite to campain" doesn't appear for some reason but for my other friend it does appear.


The only thing I think was different is that he had to register(ingame username and password) while it only ask me for the username.

Any help or suggestions are appreciated. Thank you in advance to anyone who replies.

PS: When I click "invite friends" at the campaign planet selection and my friend tries to accept the invite it says he is in a different game.

Thank you for the quick response GoogleFrog.

Could you tell me what you meant about "offline mode"?

After your response we tried the following:
- Change steam to offline mode then start game
- Logout then while steam still been offline start game and try logging in
Both times it still failed to sync.