script not working in 1.8, but same working in 1.7

script not working in 1.8, but same working in 1.7

$('#a a')
.css( {backgroundPosition: "-20px 35px"} )
.mouseover(function(){
            $(this).stop().animate({backgroundPosition:"(-20px 94px)"}, {duration:500})
        })
        .mouseout(function(){
            $(this).stop().animate({backgroundPosition:"(40px 35px)"}, {duration:200, complete:function(){
                $(this).css({backgroundPosition: "-20px 35px"})
            }})
        })


Anyone please tell why?

Thanks