[samba] Unable to connect to Samba server

[David P.]

I'm trying to access the filesystem of a Samba share from Linux.
I don't have access to the remote Samba server, but I have guessed that it 
is:

Samba 3.0.33-3.28.el5

by issuing

smbclient -L myserver

If I issue this command:

smbclient //myserver/myshare mypassword -U mydomain\\myuser -d 10

these are the most relevant error messages:

Failed to get kerberos credentials: kinit for myuser на mydomain failed (Cannot 
contact any KDC for requested realm)
Cannot reach a KDC we require to contact cifs/saprepository@ : kinit for 
myuser на mydomain failed (Cannot contact any KDC for requested realm)
Connection to \\myserver\myshare failed - NT_STATUS_LOGON_FAILURE


I have tried with the latest 4.0.6 version and also 3.6.9.

On the other hand from Windows XP and Windows 7 it works flawlessly.
Why cannot I access the Linux Sambar server from Linux and I can from 
Windows?

Thanks in advance for any help.

David