jquery hover any element changes img in one element

jquery hover any element changes img in one element

I really cannot see why this shouldnt work, comments please?

<head>
    <script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
    <script>
        $document.ready(function(){
            $('.doit').hover(function(){
                $('#cy > img').attr('src', '/images/7.png');
            });
        });
    </script>
</head>
<body>
 <div id="tasc" class="doit"><a href=""><img src="/images/1.jpg" alt="tasc"/></a></div>
            <div id="dsc" class="doit"><a href=""><img src="/images/2.jpg" alt="dsc"/></a></div>
            <div id="tma" class="doit"><a href=""><img src="/images/3.jpg" alt="tma"/></a></div>
            <div id="lta" class="doit"><a href=""><img src="/images/4.jpg" alt="lta"/></a></div>
            <div id="hsm" class="doit"><a href=""><img src="/images/5.jpg" alt="hsm"/></a></div>
            <div id="cy" class="doit"><a href=""><img src="/images/6.png" alt="cy" /></a></div>
</div>
</body>

As far as I can figure it hover over any of the divs should change #cy >img from 6 to 7 but it doesn't