KSE is looking for your saves directory and can't find it.
Originally Posted by tk102
To temporarily fix the problem...right click on the main TSL node
and then KSE will ask you where you installed the game.
The folder you point to will be inspected by KSE. It will expect to find certain directories and files there. For details read the kse-readme.txt. If something in that file is unclear, quote the part and I'll try to explain it.
Or just re-install the game.