what could be missing? can not add domain user to local administrators on one DMZ server

Hi all,

We have one member server (windows 2003)at DMZ at location B.  It has joined domain.
The DC (windows 2008 R2) is located at coporate location A.  the following firewall ports have been opened
between A and B.  It takes about 5 min to logon to DMZ server by using domain account.
Also, I tried to add domain user to local administrators group and got "
there are no more endpoints available from the endpoint mapper."

telnet server 135 is open on one domain controller and DMZ server.

What could be missing?

UDP      domain            53
TCP      domain            53
UDP      Kerberos            88
TCP      Kerberos            88
UDP      Time                  123
TCP      Kerberos Auth      135
UDP      netbios-ns            137
TCP      netbios-ssn            139
TCP      ldap                  389
UDP      ldap                  389
TCP      microsoft-ds            445
TCP      ldap to GC            3268
TCP 3269