PHP upload script ?

Hej Eksperter.
Er der nogen der kan fortælle mig hvorfor jeg får fejlen:

Warning: mkdir(../gfx/down/): File exists in /www/lonetower.dk/downfileadd.php on line 33
upload_files directory doesn't exist and creation failed

ud fra denne kode:

<?php
//vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
// You may change maxsize, and allowable upload file types.
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
//Mmaximum file size. You may increase or decrease.
$MAX_SIZE = 20000000000000;

//Allowable file ext. names. you may add more extension names.
$FILE_EXTS = array('.zip','.rar','.iso','.doc','.txt','.wmv','.avi','.mpg','.mpeg','.rm','.mov','.tar','.tar.bz2','.jpg','.png','.psd','.gif','.bmp','.jpeg','.ico');

//Allow file delete? no, if only allow upload only
$DELETABLE = false;


//vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
// Do not touch the below if you are not confident.
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
/************************************************************
* Setup variables
************************************************************/
$site_name = $_SERVER['HTTP_HOST'];
$url_dir = " http://".$_SERVER['HTTP_HOST'].dirname($_SERV...
$url_this = " http://".$_SERVER['HTTP_HOST'].$_SERVER['PHP_...

$upload_dir = "../gfx/down/";
$upload_url = $url_dir."/../gfx/down/";
$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] && $DELETABLE) {
$resource = fopen("log.txt","a");
fwrite($resource,date("Ymd h:i:s")."DELETE - $_SERVER[REMOTE_ADDR]"."$_REQUEST[del] ");
fclose($resource);

if (strpos($_REQUEST[del],"/.")>0); //possible hacking
else if (strpos($_REQUEST[del],$upload_dir) === false); //possible hacking
else if (substr($_REQUEST[del],0,6)==$upload_dir) {
unlink($_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']." "
.$_FILES['userfile']['type']." ");
fclose($resource);

$file_type = $_FILES['userfile']['type'];
$file_name = $_FILES['userfile']['name'];
$file_ext = strtolower(substr($file_name,strrpos($file_name,".")));

//File Size Check
if ( $_FILES['userfile']['size'] > $MAX_SIZE)
$message = "The file size is over 2MB.";
//File Extension Check
else if (!in_array($file_ext, $FILE_EXTS))
$message = "Sorry, $file_name($file_type) is not allowed to be uploaded.";
else
$message = do_upload($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)) {
$filelist .= "<a href='$upload_dir$file'>".$file."</a>";
if ($DELETABLE)
$filelist .= " <a href='?del=$upload_dir".urlencode($file)."' title='delete'>x</a>";
$filelist .= "_{<small><small><font color=grey> ".date("d-m H:i", filemtime($upload_dir.$file))
."</font></small></small>}";
$filelist .="<br>";
}
}

function do_upload($upload_dir, $upload_url) {

$temp_name = $_FILES['userfile']['tmp_name'];
$file_name = $_FILES['userfile']['name'];
$file_name = str_replace("\","",$file_name);
$file_name = str_replace("'","",$file_name);
$file_path = $upload_dir.$file_name;

//File Name Check
if ( $file_name =="") {
$message = "Invalid File Name Specified";
return $message;
}

$result = move_uploaded_file($temp_name, $file_path);
if (!chmod($file_path,0777))
$message = "change permission to 777 failed.";
else
$message = ($result)?"$file_name uploaded successfully." :
"Somthing is wrong with uploading a file.";
return $message;
}

?>

<center>
<H3>Download files</H3>
<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><b>Download files</b>
<hr width=70%>
<?=$filelist?>
<hr width=70%>
</center>

Mvh. WaY3000