PHPMailer AddStringAttachment with PDF

PHPMailer AddStringAttachment with PDF

I am new to phpmailer and I am able to send emails, emails with
attachments, and stringattachments that are .txt files however I cannot
send stringattachments with PDF's. The email is sent, but the PDF is
corrupted/unable to open. Can anyone help to send the AddStringAttachment
with the attachment being a PDF rather than a .txt? Thanks
<?php
require_once('class.phpmailer.php');
$mail = new PHPMailer();
$body2 = "You are receiving this email because the Transfer Application
submitted for $Name transferring to $Receiving is missing required
documentation.
Please see the note below for details. The transfer application will not
be reviewed until all of the necessary materials are received by the
UHSAA.
<p> Details:
$Notes ";
$mail->IsSMTP();
$mail->AddAddress($emailp);
$mail->AddCC('transfers@uhsaa.org');
$mail->AddStringAttachment($body2, 'Filename.pdf', 'base64',
'application/octet-stream');
$mail->Subject = "Test";
$body = ("See attachment");
$mail->MsgHTML($body);
$mail->AddAddress($address);
$mail->AddCC($address);
if(!$mail->Send())
;
?>
Again, if I just change Filename.pdf to Filename.txt everything works so
I'm assuming the problem is with the encoding but I can't figure it out.
Please help so I can send stringattachment PDF's. Thanks.