There is something going on here that you are not telling us. In your first post you show this coding . . .
SpinnerBinomi.Visible = False
Activity.AddView(SpinnerBinomi, 20dip, 42dip, Activity.Width - 20dip, 40dip)
That is, you add a spinner to your activity, but for some reason you make it invisible. Then you show us what looks like a screen shot with what looks like a spinner in the top left corner. This is not SpinnerBinomi because that view is hidden. Your coding refers only to SpinnerBinomi. What does your layout contain?
Why are you not simply adding SpinnerBinomi to the activity in the position that you want; in the centre, for example - and making it visible?
Edit : I have attached a demo project. There is a button; each time that you click it a spinner, near the centre of the screen, appears or disappears.