problem with extract rar

[yosii]

this is my code

<?php


  $zip = new ZipArchive();
  
  $zip = new ZipArchive();
if($zip->open("C.zip",ZIPARCHIVE::CREATE)===TRUE)
{
$dir = scandir('test/');
$new_dir='test/';
$num=count($dir);
for($k=0; $k<=$num; $k++)
{
	if (@$dir[$k]!="." && @$dir[$k]!="" && @$dir[$k]!=".." && @$dir[$k]!="Thumbs.db")
	{	$new_file=$new_dir.$dir[$k]; echo $new_file.'<BR>';
		$zip->addFile($new_file);
	}
}




   

   $zip->close();
$file = "C.zip";
header ("Content-Type: application/octet-stream");
header ("Accept-Ranges: bytes");
header ("Content-Length: ".filesize($file));
header ("Content-Disposition: attachment; filename=".$file);  
readfile($file);
}
  ?>

what i want is to download folder in rar and becuase of that i run FOR that read and add all my file to the function

so....

it is download good  and if i enter to the RAR file i see the file that in there...GOOD

but when i tried to extract the file i get problem in RAR

The archive is either in unknown format or damaged

why????

if I do this code diffrend and choose file by file like

<?php


  $zip = new ZipArchive();
  
  $zip = new ZipArchive();
if($zip->open("S.zip",ZIPARCHIVE::CREATE)===TRUE)
{
$zip->addFile('test/1.GIF');
$zip->addFile('test/2.GIF');	
$zip->addFile('test/3.GIF');


   

   $zip->close();
$file = "S.zip";
header ("Content-Type: application/octet-stream");
header ("Accept-Ranges: bytes");
header ("Content-Length: ".filesize($file));
header ("Content-Disposition: attachment; filename=".$file);  
readfile($file);
}
  ?>

this work good

that the problem in the FOR that run on all the folder that make problem when i extract the files..

thank