Animated view passes behind others views

Hi !

I have an animated view and a strange behavior in my application. If i do this, my view moves with an animation and passed behind others views randomly.

imgSelector.animate({
                top : newtop,
                duration : 500
            });

If i do this, my view moves without animation and is correctly displayed :

imgSelector.top = newtop;

I have no idea why the animation interact with view position or zIndex. I tried to force zIndex, readd view etc. without success.

TY