Problem is that you installed it wrong, you have two mods folders instead of one:
C:\Program Files (x86)\Steam\steamapps\common\Medieval II Total War\mods\mods\Third_Age_3.
1. Uninstall MOS using Start\ All Programs\ MOS 1.4\ Uninstall.
2. Uninstall TATW using Control Panel\ Uninstall Program.
3.Delete manually that second mods\Third_Age_3 folder which is not needed in C:\Program Files (x86)\Steam\steamapps\common\Medieval II Total War\mods\ folder.
4. Unhide hidden folders (follow this How to Unhide hidden folders on Windows: http://www.twcenter.net/forums/showt...59#post8287059)
If you can`t see the picture in that post, then this is how to do it:
On your DESKTOP, click on START in the bottom left corner, in Search Programs and Files type in Folder Options, click on Folder Options, go to VIEW section, and in Hidden files and folders check the box next to SHOW hidden files, folders or drives. Apply, and OK.
5. THIS IS IMPORTANT: disable UAC (http://www.twcenter.net/forums/showt...59#post8287059) go to section `How to fix it` and apply step 3 for this main Medieval 2 TW folder: C:\Program Files (x86)\Steam\steamapps\common\Medieval II Total War
6.Use this method to install TATW:
If you want to install MOS too, use this method:
1. Download the version you want ( either FULL INSTALLER or MORE THAN ONE PART version).
Just don`t download into your M2TW folder!
2. Double mouse click on MOS INSTALLER\ INSTALLERS, use the ˝........˝ button to browse MOS INSTALLER\ INSTALLERS to the location of your Third_Age_3 folder ( in STEAM case, it should be Steam/ Steamapps/ Common/ Medieval II Total War/ mods/ YOUR RENAMED KINGDOMS CAMPAIGN).
3. Run Cleaner.bat after installing each part, and after installing each patch.
4. Use the Steam menu to launch your MOS\ RENAMED KINGDOMS.