How do you....

[Ibn-Khaldun]

HI,

If you want to unlock other factions then the descr_strat.txt beginning should look something like this ...

Spoiler Alert, click show to read: 

campaign imperial_campaign
playable
england
france
hre
spain
venice
sicily
milan
scotland
byzantium
russia
moors
turks
egypt
denmark
portugal
poland
hungary

end
unlockable
end
nonplayable
papal_states
aztecs
mongols
timurids
slave
end

Now .. if your file looks like that and you still can't play them then someone smarter should give you advice ..