Positioning Oval
 

I am trying to position a circle (ShapeOval) in the center of a cell. My
base method is to take (CellWidth - OvalWidth)/2 as the left offset. I do
the same for the top offset. The left offset works fine. For some reason
the top offset only works as desired when the circle is approximately greater
than or equal to 1/2 to cell height. What is going on and how do I fix this?

Thanks in advance.