FINALLY GOT IT! From the Poser manual: When created bones, two children groups can not touch! A child polygons must not touch another childs polygons or ripping or displacement can occur. That was what I was doing wrong Thanks to xantor for telling me first. Sorry it took me so long to get what you were saying. My fishy can now open and close his mouth. BTW, its the Rockfish model I reboned. Any way I can distribute what I did without violating the Rockfish copyright? The default models mouth didn't open and close. One great side effect of this hair pulling is in the process I learned the Joint Editor pretty well and can see the power of it. Thanks to xantor and everyone else that helped =-)