sorry, ma non funziona:

dove ho sbagliato?

<html>
<head>
<title>Untitled</title>
</head>
<script language="JavaScript">
function change(){
document.getElementById('ok').setAttribute('onmous eover', "alert('cucu');");
}
</script>
<body>



<input type="Button" id="ok" value="OK" style="width:80;height:25" onmouseover="" >
<input type="Button" value="change onclick" style="width:120;height:25" onclick="change();">
</body>
</html>