If you downloaded mod compatible hilts they won't work in base
put them in JediPlus, Omnimod or forceMod folder
for normal lightsaber hilts
put ONE at the time in your base folder, to work
.. actually you can put mod compatible hilts in the base folder still. I do it all the time ... then u either select them from the mod hilt's list or type the path name in the console! If its a normal hilt ..... i cant help you there cause im used to Mods!