i am a newbie linux enthusiastic. I recently installed samba4 on Ubuntu 13.04 but experienced post installation error

bobby@bobby-Aspire-4732Z:~$ sudo apt-get install samba4

Reading package lists... Done

Building dependency tree       

Reading state information... Done

samba4 is already the newest version.

0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

1 not fully installed or removed.

After this operation, 0 B of additional disk space will be used.

Do you want to continue [Y/n]? y

Setting up samba4 (4.0.3+dfsg1-0.1ubuntu1) ...

ERROR(<type 'exceptions.ValueError'>): uncaught exception - unable to parse dn string

File "/usr/lib/python2.7/dist-packages/samba/netcmd/__init__.py", line 175, in _run

return self.run(*args, **kwargs)

File "/usr/lib/python2.7/dist-packages/samba/netcmd/dbcheck.py", line 108, in run

fix=fix, yes=yes, quiet=quiet, in_transaction=started_transaction)

File "/usr/lib/python2.7/dist-packages/samba/dbchecker.py", line 58, in __init__

self.infrastructure_dn = ldb.Dn(samdb, "CN=Infrastructure," + samdb.domain_dn())

dpkg: error processing samba4 (--configure):

subprocess installed post-installation script returned error exit status 255

Errors were encountered while processing:

samba4

E: Sub-process /usr/bin/dpkg returned an error code (1)

bobby@bobby-Aspire-4732Z:~$

Have anyone ever experienced this before and may I suggest your explanation.
Thank you before.

Regards,
Bobby