Upload file che non funzia

[metatad]

Ho un problema di upload file...
Questo è il codice della classe:

<?PHP
class UploadFile {
    private $upload_dir;
    private $max_file_size;
    private $files_type;
    private $max_size;
    public function __construct(){
        $this->max_size = 5242880; 
        $ext_str = "pdf,doc,rtf,zip";
        $this->files_type = explode(",",$ext_str);
    }
    public function upload_file($upload_dir="", $file_name=""){
        if(!$_FILES[error])
            foreach($_FILES as $form_name=>$file_arr)
                $this->file = $file_arr;
        if($file_name)
            $this->name = $file_name;
        else
            $this->name = $this->file['name'];
        if($upload_dir){
            if(is_dir($upload_dir))
                $this->upload_dir = $upload_dir;
            else
                return "Invalid Directory!";
        } else
            $this->upload_dir = "./";        
        $ext = substr($this->file['name'], strrpos($this->file['name'], '.') + 1);
        if (in_array($ext, $this->files_type) ) {
            if($this->file['size']<=$this->max_size){
                if (move_uploaded_file($this->file['tmp_name'],$this->upload_dir ."/". $this->name)) {
                    return "File Uploaded!";
                } else {
                    return "File uploading error!";
                }
            } else {
                return "File size should be up to 5 mb!";
            }
        } else {
            return "Invalid filetype!";
        }
    }
}
?>

Quando faccio il test, mi restituisce questo errore:

Warning: move_uploaded_file(./upload//STATUTO COORDINAMENTO.pdf) [function.move-uploaded-file]: failed to open stream: Permission denied in D:\Inetpub\webs\itcscotellaroit\nuovo\upload.class .php on line 31
Warning: move_uploaded_file() [function.move-uploaded-file]: Unable to move 'C:\PHP\upload\php57FB.tmp' to './upload//STATUTO COORDINAMENTO.pdf' in D:\Inetpub\webs\itcscotellaroit\nuovo\upload.class .php on line 31 File uploading error!

La riga 31 è: if (move_uploaded_file($this->file['tmp_name'],$this->upload_dir ."/". $this->name)) {
La cartella di destinazione, upload, ha tutti i permessi (CHMOD 777)...

Ho provato anche correggendo la riga così:

if (move_uploaded_file($this->file['tmp_name'],$this->upload_dir . $this->name)) { 

visto che nel messaggio di errore mi dava un doppio slash prima del nome file, ma l'errore si ripete.
Nel file di input, la cartella di destinazione è definita così:

$up_obj = new UploadFile();         
echo $up_obj->upload_file("./upload/");         
exit; 

Se invece scrivo:

echo $up_obj->upload_file("http://www.itcscotellaro.it/nuovo/upload/"); 

mi dice: Invalid Directory!