Or alternatively do this.
1) Go to C:\Program Files\Steam\SteamApps\common\empire total war\data.
2) Make a folder and call it backup.
3) Copy main.pack and paste it in the backup folder.
4) Open the original main.pack using the PackFileManager.exe by going to FILE>OPEN.
5) Find + db and click/expand it.
6) Scroll down the list and find units_to_special_editions_juncs_tables.
7) Right click units_to_special_editions_juncs_tables and click Delete File.
8) Click FILE>SAVE and thats it!
The instruction is very clear to me, even a white mice can do it.