mkdir - how to debug

[eluser]Shella[/eluser]
Hi there,
I'm working on a function that should write a folder.
Actually I'm in localhost with a FileZilla Server.

Don't want to waste your time so I will be quick ;-)

This is the initial part of the function:

Code:

function do_upload($member_id){
  
  /* Creazione */
  $this->load->library('ftp');
  // Variabili in constant.php
  $config['hostname'] = FTP_HOSTNAME;
  $config['username'] = FTP_USERNAME;
  $config['password'] = FTP_PASS;
  $config['debug'] = TRUE;
  
  $this->ftp->connect($config);
  
  
  $dirname = $member_id;
  
  //$this->ftp->mkdir($dirname.'', DIR_WRITE_MODE);
  //$this->ftp->mkdir($dirname.'/thumbs', DIR_WRITE_MODE);
  $this->ftp->mkdir('userspix/'.$dirname);
  $this->ftp->mkdir('userspix/'.$dirname.'/thumbs');
  
  $this->ftp->close();

....and this is the error message I got:

Unable to create the directory you have specified.

My question is: how can I understand where CI is trying to write the dirs? In other cases this function works fine!!!

thanks!