Sending a track to LFE only - help!

Hello all!
 
Have a mix for a film I am doing. I created a 5.1 channel sub-mix in a separate project, mixed it down to 6 separate .wav files, then imported it into my master mix. It was easy enough to assign each track to L,C,R,Ls, and Rs. However, I can't figure out any way to assign the rendered LFE track to the LFE output only in the Surround Bus or Surround Panner.
 
Any ideas? Seems like not matter what I do I get sound from at least one channel other than the LFE channel. Also, the LFE Solo button has no effect when I toggle it on and off.
 
So - how do I assign a specific track to LFE only???
 
Thanks in advance!
 
John