popup javascript ไม่ทำงานเมื่อใส่ Query String ไปด้วยครับ

<form name="form1" method="post" action="">
                <?php 
				
	$sql="SELECT * FROM insert_date";
$result = mysql_query($sql)or die ("NO DATA");
$data = mysql_fetch_array($result);

$str = $data['insert_date'];
$sub = substr($str,9,10);
				?>
                <input type='hidden' name='Day' value='<?=$sub?>' id='day'>
				<a href=""><img src="mos-css/img/detail.png" width="16" height="16"  alt="" OnClick="javascript:window.open('popup.php?s='+document.form1.Day.value,'popup-name','width=700,height=500,toolbar=0, menubar=0,location=0,status=1,scrollbars=1,resizable=1,left=0,top=0');"/></a> </form>