Key frames not working with appearance effect of a shape

[JakesMakes]

I have a shape (an oval, not that you needed to know that) that I am shrinking in size with the scale setting. To stop the stroke size from appearing to shrink I have attempted to use key frames in order to increase the stroke size as the shape scales down so the stroke seems to stay the same. However this does not work.

[Ann Bens]

It is important to know if you are using ovals or a rectangular, as stroke in the latter can behave differently to ovals.

Use two ovals superimposed instead of a stroke.