PHP PDF display from SQL Server on IIS

Question

I have this code that uploads a PDF into a SQL Server database

$attach_Name = $_FILES['aFile']['name'];
$attach_Name = str_replace("'","",$attach_Name);
$attach_Name = str_replace("\"","",$attach_Name);
$attach_Data = file_get_contents($_FILES['aFile']['tmp_name']);
$attach_Data = base64_encode($attach_Data);

And the SQL is:

INSERT INTO [dB].[dbo].[Doc_Data] ([DocInfoId],[DocData]) VALUES ('1',CAST('".$attach_Data."' AS 
VARBINARY(MAX)))

Then to retrieve and display it I use the following:

 $dbh = new PDO ('sqlsrv:server='.$dbServer.';database='.$dbName.'',''.$dbUN.'',''.$dbPass.'');
 $result = $dbh->prepare("SELECT [Doc_Data].[DocData]
                    FROM [dB].[dbo].[Doc_Data] 
                    WHERE [Doc_Info].[KeyID] ='1' 
 ");
 $result->execute();
 $row = $result->fetch(PDO::FETCH_ASSOC);

 $attach_Data = base64_decode($row['DocData']);
 $myfile = $row['DocName'];
 $myfile = str_replace(" ", "_", $myfile);
 $handle = fopen($myfile, "w+") ;//or die("Unable to open file!");
 $disp = fwrite($handle, $attach_Data);
 $type = filetype($myfile);
 $mode = "inline";
 header('Content-type: application/pdf');  
 header('Content-Disposition: inline; filename="' . $myfile . '"'); 
 header('Content-Transfer-Encoding: binary');
 header('Accept-Ranges: bytes');

// Read the file
@readfile($myfile);

fclose($handle);
unlink($myfile);
exit;

$dbh = null;

This works perfectly on Apache (XAMPP) but the client has moved to IIS and now my code fails to render the PDF anymore.

Any suggestions?