SetAlpha Behaving Weird

I have added a view with special params using windowmanager, it overlays the screen and I am trying to change the alpha of this view using a seekbar. I have tried changing the alph

Solution 1:

Open()

mOverlayView .animate().scaleX(1.0f).scaleY(1.0f).setDuration(200)
                .start();
        mOverlayView .setAlpha(0.5f);

Close()

mOverlayView .animate().scaleX(0f).scaleY(0f).setDuration(200).start();