It doesnt show up on the game as a new campaign option tho its installed and tagged as such on the games configure page.

Same here!
What gives????


Launching it through Galaxy and the rest of the game works fine, but no 4'th campaign!

I found the answer:
The 'campaign' screen isn't a campaign screen at all... it's the save game screen.

To make it work, you need to delete one of your old compaigns, then start a new game and it'll be in there, to the left of Two Crowns.