I got the MTW2 Defenitive Edition from Steam.
I installed the 3 main mod files.
I have the SicilianVespers mod folder.
I renamed it "teutonic" to be able to let Steam run it.
It works.
I can play 3 era's through "Custom Campaigns".
Just not the Dark Age era. The game keeps throwing me back to the Era menu when I choose that.
Since you cannot start the game through the Launcher, is there a fix to get to the Dark Ages?