Animate scrollTop not working in firefox

This function works fine. It scrolls the body to a desired container's offset

function scrolear(destino){
    var stop = $(destino).offset().top;
    var delay = 1000;
    $('body').animate({scrollTop: stop}, delay);
    return false;
}

But not in Firefox. Why?

-EDIT-

To handle de double trigger in the accepted answer, I suggest stoping the element before the animation:

$('body,html').stop(true,true).animate({scrollTop: stop}, delay);