为什么PHPMailer显示Failed to move file错误消息

我使用PHPMailer从localhost发送电子邮件。我正在使用附件选项通过电子邮件发送图像。但它显示了以下错误信息：

错误消息：

Failed to move file to C:'Users'Work Station'AppData'Local'Temp'3c3D24E.tmp

我的代码：

require '../PHPMailerAutoload.php';
$m =  new PHPMailer();
$m->isSMTP();
$m->SMTPAuth = true;
//$m->SMTPDebug = 2;
$m->Host = gethostbyname('smtp.gmail.com');
$m->Username = 'username';
$m->Password = 'password';
$m->SMTPSecure =  'ssl';
$m->Port = 465;
$m->From = 'support@from.com';
$m->FromName = 'Shibbir Ahmed';
$m->addReplyTo($to);
$m->addAddress($to, 'Shibbir Ahmed');
//Attach multiple files one by one
if(isset($_FILES['userfile'])) {
    for ($ct = 0; $ct < count($_FILES['userfile']['tmp_name']); $ct++) {
        $uploadfile = tempnam(sys_get_temp_dir(), sha1($_FILES['userfile']['name'][$ct]));
        $filename = $_FILES['userfile']['name'][$ct];
        if (move_uploaded_file($_FILES['userfile']['tmp_name'][$ct], $uploadfile)) {
            $m->addAttachment($uploadfile, $filename);
        } else {
            echo  'Failed to move file to ' . $uploadfile;
        }
    }
}
$m->Subject = $subject;
$m->Body = $message;
$m->AltBody = strip_tags($message, "<p>, <br>");