[Problema] Filereference

Tengo un problemita aquí.

Código :

var upurl = path + "/uploadfiles.php?nickname=" + nickname;
load_mc._visible = true;
load_mc.barra_mc._xscale = 0;
fileUpload.upload(upurl); 

Se puede

Código :

fileUpload.upload("/uploadfiles.php?nickname="+nickname);

?
Ya lo he intentado de todo, hasta colocar el nickname manualmente,

Código :

fileUpload.upload("/uploadfiles.php?nickname=user);

mi archivo uploadfiles.php es:

Código :

<?php 

$uploadDir = $_GET['nickname'];
$target = "$uploadDir/"; 
$target = $target . $_FILES['uploaded']['name'] ; 
$ok=1; 
if(move_uploaded_file($_FILES['uploaded']['tmp_name'], $target)) 
{
echo "The file ". $_FILES['uploadedfile']['name']. " has been uploaded";
} 
else {
echo "Sorry, there was a problem uploading your file.";
}
?>