Here's what I found about it:
http://search.yahoo.com/search?p=%22couldn%27t+add+pathfinding+sphere%22&ei=UTF-8&fr=moz2 You got markers in your collision model? Marker are for gbxmodels only
Got masspoints in your collision? Masspoints are for physics
For collision, delete the # stuff and export, but don't save, reload, and export again for physics after successfully tooling collision
I don't know if there's a special name for the collision and/or physics jms file in the physics folder. I use the same, .jms file for both