郁闷……请大家帮忙

<html>
<head>
<script language=javascript>
var checkboxer = new Array("id","type_name","OA4","OA5","OA6","OA7","OA8","OA9","OA10","OA11","OA12","OA13","OA14","OA15","OA16","OA17");
var rouer;
function chooseall(){
for(var n=0;n<checkboxer.length;n++){
rouer = checkboxer[n];
document.all(rouer).checked=true;
}
}
</script>
</head>
<body>
<form name=form1 method=post>
<table>
<tr><td><input type=checkbox name="id"        >a</td></tr> 
<tr><td><input type=checkbox name="type_name" >a</td></tr> 
<tr><td><input type=checkbox name="OA4"       >a</td></tr> 
<tr><td><input type=checkbox name="OA5"       >a</td></tr> 
<tr><td><input type=checkbox name="OA6"       >a</td></tr> 
<tr><td><input type=checkbox name="OA7"       >a</td></tr> 
<tr><td><input type=checkbox name="OA8"       >a</td></tr> 
<tr><td><input type=checkbox name="OA9"       >a</td></tr> 
<tr><td><input type=checkbox name="OA10"      >a</td></tr> 
<tr><td><input type=checkbox name="OA11"      >a</td></tr> 
<tr><td><input type=checkbox name="OA12"      >a</td></tr> 
<tr><td><input type=checkbox name="OA13"      >a</td></tr> 
<tr><td><input type=checkbox name="OA14"      >a</td></tr> 
<tr><td><input type=checkbox name="OA15"      >a</td></tr> 
<tr><td><input type=checkbox name="OA16"      >a</td></tr> 
<tr><td><input type=checkbox name="OA17"      >a</td></tr> 
<tr><td><input type=button name="button_choose" value="全选" onclick="chooseall()" ></td></tr>
</table>
</form>
</body>
</html>