Thanks for your reply Realspawn - the sphere movement is there only as a trigger point for the terrain 'passable' action - no point in making it passable.
I have tried your suggestion of:-
set(terrain, PASSABLE); ,but the terrain is as solid as ever !!
There must be a way of doing this, but I can't find it.
I have put 'beep' at the end of the action, so I know the engine is working - it's just not recognizing something in the first part of the(terrain part) of the action. Someone must know how to do this ? !!
Hopefully, David