You quite plainly did not. That you insist you did, and are unable to substantiate your claims except insisting it is so is quite revealing.
It reveals that you are out of your depth. However, since I'm such a giving person, I quote myself again for you. Seriously, try reading next time. You'll look less foolish. This is the second time you've claimed I didn't write something I did and you've been proven wrong.
The shell theorem shows that gravitational acceleration between two bodies can be calculated using the center of those bodies because, effectively, the TOTAL gravitational acceleration inside nets out to zero as can be shown using two perfectly spherical but hollow bodies and how, relative to the internal coordinates, gravitational acceleration is calculated relative to ANOTHER body either inside or external to the spherical hollow mass (that's the radius you were missing, the second body). That doesn't mean there IS NO GRAVITY or that it is not stronger inside the body in one corrdinate than in another place. It just means that it NETS to zero.
There is also a shell theorem application for electrostatic systems. A rough analogy would be that, inside the bubble of the universe, the total amount of energy = zero yet we can still utilize energy to get work done.
Also, you insinutated you could do all the math on this and that I couldn't. Please show your math.