upload script virker ikke

Hej har hentet dette upload script Hotscripts.com får følgende fejl

change permission to 755 failed.

billedet skal ligge i en mappe som er /forum/imagessalg.

nogle som kan gennemskue det?

min udbyder er B_one

<?php
$site_name = $_SERVER['HTTP_HOST'];
$url_dir = "http://".$_SERVER['HTTP_HOST'].dirname($_SERVER['PHP_SELF']);
$url_this =  "http://".$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF'];

$upload_dir = "/forum/imagessalg/";
$upload_url = $url_dir."/forum/imagessalg/";
$message ="";

/************************************************************
*    Create Upload Directory
************************************************************/
if (!is_dir("files")) {
  if (!mkdir($upload_dir))
      die ("upload_files directory doesn't exist and creation failed");
  if (!chmod($upload_dir,0755))
      die ("change permission to 755 failed.");
}

/************************************************************
*    Process User's Request
************************************************************/

if ($_REQUEST[del])  {
  $resource = fopen("log.txt","a");
  fwrite($resource,date("Ymd h:i:s")."DELETE - $_SERVER[REMOTE_ADDR]"."$_REQUEST[del]\n");
  fclose($resource);
 
  if (strpos($_REQUEST[del],"/.")>0);  //possible hacking
  else if (strpos($_REQUEST[del],"files/") === false); //possible hacking
  else if (substr($_REQUEST[del],0,6)=="files/") {
    unlink($_REQUEST[del]);
    print "<script>window.location.href='$url_this?message=deleted successfully'</script>";
  }
}
else if ($_FILES['userfile']) {
  $resource = fopen("log.txt","a");
  fwrite($resource,date("Ymd h:i:s")."UPLOAD - $_SERVER[REMOTE_ADDR]"
            .$_FILES['userfile']['name']." "
            .$_FILES['userfile']['type']."\n");
  fclose($resource);

  $message = do_upload($upload_dir, $upload_url);
  print "<script>window.location.href='$url_this?message=$message'</script>";
}
else if (!$_FILES['userfile']);
else
    $message = "Invalid File Specified.";

/************************************************************
*    List Files
************************************************************/
$handle=opendir($upload_dir);
$filelist = "";
while ($file = readdir($handle)) {
  if(!is_dir($file) && !is_link($file)) {
      $filelist .= "<br><a href='$upload_dir$file'>".$file."</a>";
      $filelist .= "    <a href='?del=$upload_dir$file' title='delete'>x</a>";
  }
}

function do_upload($upload_dir, $upload_url) {

    $temp_name = $_FILES['userfile']['tmp_name'];
    $file_name = $_FILES['userfile']['name'];
    $file_type = $_FILES['userfile']['type'];
    $file_size = $_FILES['userfile']['size'];
    $result    = $_FILES['userfile']['error'];
    $file_url  = $upload_url.$file_name;
    $file_path = $upload_dir.$file_name;

    //File Name Check
    if ( $file_name =="") {
        $message = "Invalid File Name Specified";
        return $message;
    }
    //File Size Check
    else if ( $file_size > 2000000) {
        print $file_size;
        $message = "The file size is over 1MB.";
        return $message;
    }
    //File Type Check  -- may cause possible attacks
    else if ( strpos($file_name,".php") !== false
          || strpos($file_name,".cgi") !== false
          || strpos($file_name,".htm") !== false
          || strpos($file_name,".phtm") !== false )
      return;
    else if ( strpos($file_type,"image") !== false
      || $file_type == "application/msword");
    else {
        $message = "Sorry, demo. only allows image or ms-word upload." ;
        $message .= "<br>You may allow other types(i.e, .zip) on your own server." ;
        return $message;
    }

    $result  =  move_uploaded_file($temp_name, $file_path);
    if (!chmod($file_path,0755))
        $message = "change permission to 755 failed.";
    else
      $message = ($result)?"$file_name uploaded successfully." :
                "Somthing is wrong with uploading a file.";

    return $message;
}

?>
<center>
  <font color=red><?=$_REQUEST[message]?></font>
  <br>
  <form name="upload" id="upload" ENCTYPE="multipart/form-data" method="post">
    Upload File <input type="file" id="userfile" name="userfile">
    <input type="submit" name="upload" value="Upload">
  </form>
 
  <br>
  <br><b>My Files</b>
  <hr width=70%>
  <?=$filelist?>
</center>

<?
if ($_REQUEST[debug]==1) print "------------------Debugging Info----------------<br>";
if ($_REQUEST[debug]==1) print "site=$site_name<br>dir=$url_dir<br>url=$url_this<br>";
if ($_REQUEST[debug]==1) print "upload dir=$upload_dir<br>upload url=$upload_url<br>";
?>