Ok … I gotta solve (in parts) my problem … I saw the tutorial to get a model and do animation (link: https://hub.jmonkeyengine.org/t/tutorial-cadnav-to-mixamo-to-jme-workflow/35356). I think I understood what DarkChaos meant about the submodel. And my code looks like this:
Node nod=(Node) assetManager.loadModel(//File);
Spatial spt=nod.getChild(0);
rootNode.attachChild(spt);
control=spt.getControl(AnimControl.class); // AnimControl control=null
The remainder is the default procedure, creates AnimChannel, and so on.
Now when I run the animation, the camera moves down, and it stops. (I know the animation is running because I put it to show a message when the animation closes.