samba4 join as DC fails with NT_STATUS_ERROR_DS_OBJ_STRING_NAME_EXISTS

[soomon]

hi there,

I hope this is the right mailing list... if not just tell me which one to
use. thanks :D

I just installed Samba4 with this tutorial:
http://wiki.samba.org/index.php/Samba4/HOWTO
till step 3. then switched to:
http://wiki.samba.org/index.php/Samba4_joining_a_domain
but when joining the existimg domain as a DC i get:

root at ubuntusamba4:/home/soomon/samba-master/source4# bin/net vampire
internal.domain.com -Uadministrator --realm=internal.domain.com
Password for [WORKGROUP\administrator]:
Become DC [(null)] of Domain[INTERNAL]/[internal.domain.com]
Promotion Partner is Server[domaincontroller.internal.domain.com] from
Site[ourplace]
Options:crossRef behavior_version[2]
    schema object_version[44]
    domain behavior_version[2]
    domain w2k3_update_revision[9]
libnet_BecomeDC() failed - NT_STATUS_ERROR_DS_OBJ_STRING_NAME_EXISTS
Vampire of domain failed: NT_STATUS_ERROR_DS_OBJ_STRING_NAME_EXISTS
return code = -1

domain functional level is server 2003.
I have to admit that I had to try this command several times because of a
missing directory within  /usr/local/...
the computer account is created in the domain (I can see it on the windows
server).

but wheat's the problem? which object already exists? does it refer to an
object on a windows server or on the samba side?

thanks & greets,
soomon