[Samba] Trouble with User Management

[remote]

Hi all !

I am trying to setup a Samba 3 server which allows WinXP machines to access directories on a Linux box. So far, I have managed to set upa stand-alone server with a public share which can be read by everybody in the Windows Neighborhood. What I want to do, though, is to have some kind of user management, so that only the person who owns a Linux directory in the share can access it via his or her Windows machine. 
Unfortunately, I can´t get it to work : the server asks me for a Username/Password, but won´t accept it. Right now, I am testing my setup with a single directory I want to import to the Windows network. Since both my Windows User and my Linux user have the same username and password (I also created a SMB user with smbpasswd -a...) I don´t understand why Samba should deny my authorization. Neither log.nmbd nor log.smbd show anything about authorization troubles.

My smb.conf : 

 [global]
workgroup = leat
netbios name = nimloth
server string = Nimloth SAMBA Server
security = user
local master = no
encrypt passwords = yes
username map = /etc/samba/smbusers

[LoraFlox]
comment = LoraFlox
valid users = leichejo
guest ok = No 
path = /net/nimloth/disc1/projekte/loraflox
read only = No
guest ok = No
browseable = Yes

my smbusers

#root = administrator admin
leichejo = leichejo BALIN/leichejo 
#nobody = guest pcguest smbguest

Any ideas ? As you might have noticed, I am pretty new to Samba.

Thanks for the help,

Jörg