File name cannot be empty ftp_get

Question

Downloading multiple files from ftp and files are present on server, My code works and prints the filename from ftp but cant download the file.

$login_result = ftp_login($con, $server['stager_usr'], $server['stager_pwd']);
ftp_pasv($con, true);

$now = time();
$yesterday = $now - (24 * 60 * 60);
$date = date("Y-m-d", $yesterday);
if (isset($_GET['date'])) {
    $date = $_GET['date'];
}

$date_dir = strftime("/%Y-%m-%d", $yesterday);
$date_dir = $server['basedir'].$date_dir;

$path =  $server['basedir'];

$serverDir = $_SERVER['DOCUMENT_ROOT'];
$imagesTop = "/CSV";


$startDate = "$date 00:00:00";
$endDate = "$date 23:59:59";

$files = ftp_nlist($con,$date_dir);
$date_dir =  strftime("%Y-%m-%d", $yesterday);
$date_dir = $path . $date_dir;
  foreach ($files as  $file)
 {
        if (preg_match("/\.csv$/i", $file))
        {
            echo"\n  Found $file \n";
              ftp_get($con, $serverDir, $file, FTP_BINARY);
           }

      }
}



 ftp_close($con);
}
}

//}
?

PHP Warning: ftp_get(): Filename cannot be empty in /usr/local/bin/camftp.php o n line 126 PHP Warning: ftp_get(): Error opening in /usr/local/bin/camftp.php on line 126