Don't know if the following is of any interest to you, but I thought I would pass it on just in case, as it does relate to the actor line in the mt5.

You have gotten me interested now, I like a good mystery. I did some experiments with the Poser primitives in P6.

Loaded a box prop, applied the GROUND texture, sved an MT5. Edited the MT5 to read:

actor box_1
 {
 material xxx

Loaded new scene with Jessi and several Poser box props, some parented to Jessi.

The MT5  worked on any selected box, and on  the figure. I then loaded some more props, cones cylinders, etc, the MT5 worked on everything.

I edited the the MT5 to reffer to a ball prop:

actor ball_1
 {
 material xxx

I Reverted to the original scene with Jessi and the boxes. Now the MT5 would not work on anything! I added a ball prop to the scene. Now the MT5 worked on everything again.

I'm not sure what conclusions to draw from this, other than that the actor name is significant, and that it seems that an actor with the name used in the MT5 must exist in the scene before the MT5 will work. I haven't done any experiments using body part names as yet.

The material name seems to be irrelivent, you can even leave it blank, but there must be a 'material' statement, eg:

actor $CURRENT
 {
 material