I am trying to model a simple textbook problem: insulating spherical ball inside of the constant electric field 
[Ref: Griffiths Introduction to electrodynamics 3rd ed Chapter 4.4.2]. You can see the example problem from here
From the solution, electric field inside of the insulator is,
Equation shows that the electric field inside of the insulator should be depend on the relative permitivity. However, my simulation shows different result.
I simulate this problem by two stanless steel plate inside of the air. I insert the insulating sphere and change the property of the material. I attached three simulation files; one is with No sphere (the air property of sphere), another one is with the sphere with a different relativive permitivity, and the other one is with the sphere with a different relativie permitivity and conductivity.
From the simulation, I found that the field is depend on the conductivity, but there is no dependence of the relative permivitiy. Could anyone tell me what am I doing wrong?