Thats because you have to start with forces not energy ... this sort of leads back to the above problem. For energy to be measured you first have to produce a force against something and that takes us to the four fundemental forces (
http://library.thinkquest.org/27930/forces.htm)
So for your orbital problem we have two forces
Gravity trying to pull the objects together (A fundemental force)
Centrifugal force trying to throw the objects apart (A fictional force born of motion)
Viewed like that at any point in the orbit those two forces are balanced. The energy flow is a side product of the forces. This will help you can view the energy and forces etc (http://www.phys.hawaii.edu/~teb/java/ntnujava/Kepler/Kepler.html). If you turn it into energy display it will show you the flow the calc is down below.
This is sort of what I was saying at the start you can't really start with energy because there is no directionality in energy you can't balance things into cycles.
Forces are directional they are always the start point we tend to think energy is but that is wrong. Every motor, every system we make we impart directionality to make them start .... a car engine can go backwards if not timed properly and the starter motor starts it rolling forward. I know of not to many things that will start without at least a gentle nudge to impart the direction we want it to go.
And that leads us back to the start ... in the universe what is the force pushing against and why the directionality.
