Ok, first check that you have the file "planes.txt" in the same directory as FSHostClient. If you're using a shortcut to FSHostClient, try running FSHostClient directly, without the shortcut.
Second, it's having trouble finding where you've installed FSX. Go to Edit / Options in FSHostClient, and turn on "Log debug messages" and "Log debug errors", and then try it again. It should give us more info about what's happening.