งงครับ...งงครับ..ทำไมมันไม่ echo script ออกมา ทั้งที่ก็รับค่ามาได้แล้วนะครับ

$result = mssql_query($sql);
$num_rows=mssql_num_rows($result);

$result = mysql_query($sql);
$num_rows=mysql_num_rows($result);

echo $num_rows;

<?
$username=$_POST['username'];
//echo $username;
include('config.inc.php');
$sql= "select count(*) from userin where logname='$username' ";
$result = mssql_query($sql);
//echo $result;
//$num_rows=mssql_num_rows($result);
			if($result==1) 
		{echo "<script>alert('username ซ้ำ');window.location = 'log.php';</script>";
		}
		else
		{echo "<script>alert('username ไม่ซ้ำ');window.location = 'log.php';</script>";
		}
		
?>

$sql= "select count(*) as count  from userin where logname='$username' ";
$result = mssql_query($sql);
$count = mssql_result($result,0,'count');
//echo $result;
//$num_rows=mssql_num_rows($result);
			if($count==1) 
		{echo "<script>alert('username ซ้ำ');window.location = 'log.php';</script>";
		}
		else
		{echo "<script>alert('username ไม่ซ้ำ');window.location = 'log.php';</script>";
		}