การใช้ php เชื่อมต่อกับ mssql 2008 ค่ะ มันขึ้น error แบบนี้ :: Unable to connect to server

<?
	$objConnect = mssql_connect(".\SQLEXPRESS","","");
	if($objConnect)
	{
		echo "Database Connected.";
	}
	else
	{
		echo "Database Connect Failed.";
	}

	mssql_close($objConnect);
?>

<?php
$dns = 'sqlsrv:Server=localhost\sqlexpress;Database=northwind;';
$dbh = new PDO($dns, '', ''); //pdo($dns, user, pass)

$query = 'SELECT EmployeeID, LastName, FirstName, Title, TitleOfCourtesy, BirthDate, Address, City, Country FROM Employees;';
$stmt = $dbh->prepare($query);
$stmt->execute();

while ($result = $stmt->fetch(PDO::FETCH_OBJ)) {
    echo '<tr>';
    echo "<td><img src=\"images/imageicon.png\" 
        onmouseover=\"javascript:showtrail('imagedb.php?db=sqlsrv&amp;id={$result->EmployeeID}');\" 
        onmouseout=\"javascript:hidetrail();\" style=\"border-width:0px;\" /></td>";
    echo "<td>{$result->TitleOfCourtesy} {$result->LastName} {$result->FirstName}</td>";
    echo "<td>{$result->Title}</td>";
    echo "<td>" . (new DateTime($result->BirthDate))->format('d M Y') . "</td>";
    echo "<td>{$result->Address}</td>";
    echo "<td>{$result->City}</td>";
    echo "<td>{$result->Country}</td>";
    echo "</tr>\n"; 
}
?>

<%php
//pdo with blob
$dns = 'sqlsrv:Server=localhost\sqlexpress;Database=northwind;';
$dbh = new PDO($dns, '', '');
        
$query = "SELECT Photo FROM Employees WHERE EmployeeID = :employeeID";
$stmt = $dbh->prepare($query);
$stmt->bindParam(':employeeID', $id, PDO::PARAM_INT);
$stmt->execute();  
        
$result = $stmt->fetch(PDO::FETCH_OBJ);
header("Content-type: image/bmp");
print substr(pack('H*', $result->Photo), 78); // remove ole header
%>

try{
$hostname = "192.168.5.11";            //host
$dbname = "dbname";                       //db name
$username = "sa";                             //username like 'sa'
$pw = "1234";                                    //password for the user
$db = new PDO ("mssql:host=$hostname;dbname=$dbname","$username","$pw");
} catch (PDOException $e) {
echo "Failed to get DB handle: " . $e->getMessage() . "\n";
exit;
}

//หรือ

$objConnect = mssql_connect("192.168.5.11","sa","1234") or die("Error Connect to Database");
$objDB = mssql_select_db("dbname");

<? 
$objConnect = mssql_connect("TFM_HR_SERVER\\sqlexpress:1433","sa","tigersoft") or die("Error Connect to Database");
$objDB = mssql_select_db("CyberHRM");
?>