I will summarize what I have understood because what you are trying to do is not obvious, but I can guess..
1) You have a Windows AD machine (assumed to be well configured DNS, etc)
2) You have a Linux Machine (Distro Not Known from your Post).
3) Now You want to become a Member of the AD. That means you want that others (windiows machines) can see/accesss shares on your linux machine
If the Above is Correct, then...
1) Yous smb.conf is absolutely wrong.
2) The Steps Are....
A) Configure the smb.conf appropriately so that you can join it to domain Look here
http://www.samba.org/samba/docs/man/...in-member.html
Read this chapter before you go ahead, specially this section
http://www.samba.org/samba/docs/man/...tml#ads-member
B) Configure /etc/krb5.conf Details are explained on the above docs
C) Do a 'net ads join'
You are Done
regards