I have seen posting on TC working on all Nikon lens, and I would like to point out that it might not be true.
Observe the image below (courtesy of Ken Rockwell Website)
The lens component is protuding, so there are alot of Nikon lens not compatible with it. You end up colliding the rear lens with this front lens of the TC.
If it is not compatible, don't attempt it. You end up damaging your lens. Also I assume there are some assumption on the positioning of the lens to the TC itself. 70-200 works fine because if you notice, the lens rear component is all the way inside the lens, even if you focus to the shortest focal length, it is still quite deep inside the lens, so it will not collide at all. Try your 18-200, you will know it doesn't even mount. Even if it does mount, you better try all focal length and make sure it doesn't touch the lens.