ftp IIS mistake

hi everyone
here is my problem:
i've 2 machines:
a server running windows 2003 server, acting as domain controller (domain
name: nlbtest.it)
a server running windows 2003 with an IIS's ftp server installed. This
second server is in the domain nlbtest.it and configured using active
directory's users, configured in "isolate users using active directory"
mode.

The problem is as follow:
when i try to logon to ftp site, i receive the following output:
-
bit@paranoia:~$ ftp 192.168.111.3
Connected to 192.168.111.3.
220-Microsoft FTP Service
220 ftp sito 2
Name (192.168.111.3:bit): ftp3@nlbtest.it <i've tried with users
ftp3 and nlbtest\ftp3
331 Password required for ftp3@nlbtest.it.
Password:
530 User ftp3@nlbtest.it cannot log in, home directory inaccessible.
ftp: Login failed.
ftp>


googling around, i rod this is a permission problem.
the home directory of ftp3 user is d: and has all permissions for every
user (administrator, domain users, ftp3, everyone, my dog too!)
i really don't know which is the real problem, please help me i'm really
desperade.
tnx everyone for your attention,
fabio