try renaming your channels to tx , ty , tz. with the default chan[1-3], i was having trouble, too. you can also input SOP to CHOPs, or use the target and reference parameters, which take Object COMPs, like a Geo.
Thanks for the heads up Matt!
I was on the forum yesterday and I literally saw you writing that post !
I have read and studied the amazing post/tutorial you wrote, downloaded the file, and already spent hours on it!!