Estoy usando el siguiente código para enviar un correo electrónico con un archivo adjunto, pero el archivo adecuado no se adjunta con el correo

$UnidID = $_COOKIE['UniqueID'];
$guid = $_COOKIE['guid'];
$target_path = "userdata/".$UniqueID."/".$iGuid."/Outputs";
$fname = getpathmail($UnidID,$guid);
$target_path = $target_path.$filname;

$fileatt_type = "application/fbf"; // File Type
$fileatt_name = $fname; 
$data = $target_path;
$email_from = "[email protected]"; 
$email_subject = "EHP/PPP process";
$email_message = "Processed result for EHP/PPP processing";

$email_to = $_GET['Email'] ; 

$headers = "From: ".$email_from;

$semi_rand = md5(time());
$mime_boundary = "==Multipart_Boundary_x{$semi_rand}x";

$headers .= "\nMIME-Version: 1.0\n" .
"Content-Type: multipart/mixed;\n" .
" boundary=\"{$mime_boundary}\"";

$email_message .= "This is a multi-part message in MIME format.\n\n" .
"--{$mime_boundary}\n" .
"Content-Type:text/html; charset=\"iso-8859-1\"\n" .
"Content-Transfer-Encoding: 7bit\n\n" .
$email_message .= "\n\n";

$data = chunk_split(base64_encode($data));

$email_message .= "--{$mime_boundary}\n" .
"Content-Type: {$fileatt_type};\n" .
" name=\"{$fileatt_name}\"\n" .
"Content-Transfer-Encoding: base64\n\n" .
$data .= "\n\n" .
"--{$mime_boundary}--\n";

$ok = @mail($email_to, $email_subject, $email_message, $headers);